Title of Invention

LUBRICATING OIL HAVING ENHANCED RESISTANCE TO OXIDATION, NITRATION AND VISCOSITY INCREASE

Abstract 1 ABSTRACT 2 3 This invention is directed to an antioxidant system for use in lubricating oils 4 comprising sulfurized isobutylene and hindered phenols that provides 5 enhanced oxidation resistance and is particularly useful in natural gas fueled 6 engines, the method for making this antioxidant system, lubricating oils 7 comprising the antioxidant system and methods for lubricating engines using 8 lubricating oil comprising this antioxidant system.
Full Text

1 LUBRICATING OIL HAVING ENHANCED
2 RESISTANCE TO OXIDATION, NITRATION
3 AND VISCOSITY INCREASE
4
5 BACKGROUND
6 This invention relates to an antioxidant system and lubricating oil
7 comprising the antioxidant system. The lubricating oil of this invention may be
8 used as a lubricant for any lubricating applicator-n, however its enhanced
9 properties makes it particularly applicable for use as a lubricant for natural gas
10 fueled engines.
11 Natural gas fueled engines are engines that use natural gas as a fuel
12 source. Lubricating oil with high resistance to oxidation, nitration and viscosity
13 increase is preferred for lubricating oils used in natural gas engines because
14 of the conditions related to this type of engine.
15 Natural gas has a higher specific heat content than liquid hydrocarbon
16 fuels and therefore it burns hotter than liquid hydrocarbon fuels under typical
17 conditions. In addition, since it is already a gas, natural gas does not cool the
!8 intake air by evaporation as liquid hydrocarbon fuel droplets do. Furthermore.
19 many natural gas fueled engines are run either at or near stoichiometric
20 conditions, where less excess air is available to dilute and cool combustion
2! gases. As a result, natural gas fueled engines generate higher combustion
22 gas temperatures than engines burning liquid hydrocarbon fuels. Since the
23 rate of formation of NOx increases exponentially with temperature, natural gas
24 fueled engines may generate NOx concentrations high enough to cause
25 severe nitration of lubricating oil.
26 In most cases, natural gas fueled engines are used continuously at
27 70 to 100% load, whereas an engine operating in vehicular service may only
28 spend 50% of its time at full load. Lubricating oil drain intervals may vary in
29 vehicular service, but are typically shorter than those for natural gas fueled
30 engines.
31 Natural gas fueled engines may be located in remote areas where
32 service is not readily available and may be expensive. Because of this it is
33 important to ensure the reliability of natural gas fueled engines. High

34 comprises an antioxidant system comprising saturated isobutylene and one or
35 more hindered phenols. The hindered phenols of this antioxidant system may
36 comprise butyrate hydroxy toluene (BHT, which is also known as 2,6-di-tert-
37 butyl-1-hydroxy-4-methylbenzene or2,6-d)-tert-butyl-para-cresol), and 3.5-di-
38 t-bulyl 4-hydroxyphenyl propionate (also known as benzenepropanoic acid,
39 3,5-bis (1,1-dimethyl-ethyl)-4-hydroxy-, C7-C9 branched alkyl esters; or 3,5-di-
40 tert-bLityl-4-hydroxyhydrocinnamic acid, C7-C9 branched alkyl ester) having
41 the general formula: 9
10
n
i2 13
14 wherein R is a C? - C9alkyl group.
15 Another embodiment of this invention is an additive formulation comprising
16 one or more of the additive systems of this invention and other additives.
17 The lubricating oil of this invention may comprise base oil and one or
IS more of the additive formulations of this invention. The lubricating oil of this
19 invention may comprise base oil and one or more of the additive systems of
20 this invention. One embodiment of this invention may comprise a method of
21 lubricating engines comprising contacting one or more of the lubricating oils of
22 this invention with one or more engines. One embodiment of this invention
23 may comprise a method of lubricating natural gas fueled engines comprising
24 contacting one or more of the lubricating oils of this invention with one or more
25 natural gas fueled engines. This invention comprises methods for making any
26 embodiments of the lubricating oil or additive systems or additive formulations
27 of this invention comprising combining the components in any order at a
28 temperature sufficient to encourage mixing of the components, but not
29 sufficient to degrade the components. This invention comprises methods for
30 making any embodiments of the lubricating oil of this invention comprising
31 combining the components in any order at a temperature of about
32 140 degrees F.
33

DETAILED DESCRIPTION OF THE INVENTION
1 This invention is directed to one or more antioxidant systems for use in
3 lubricating oils. One embodiment of the invention may be lubricating oil that
4 comprises sutfurized isobutylene as an antioxidant. Snottier embodiment of
5 the invention may be an additive formulation that comprises sulfuhzed
6 isobulyiene as an antioxidant, and one or more dispersants, one or more
7 detergents, and one or more wear inhibitors. Another embodiment of this
8 invention may be lubricating oil comprising one or more of the antioxidant
9 systems of this invention. Another embodiment of this invention may be a

10 lubricating oil comprising one or more of the additive formulations of this
11 invention. These antioxidant systems, additive formulations and lubricating
12 oils may be particularly useful in natural gas fueled engines.
13 Another embodiment of the invention may be lubricating oil that
14 comprises sulfurized isobutylene in combination with an antioxidant such as
15 hindered phenol. One embodiment of the invention may be an additive
16 formulation that comprises suifurized isobutylene, an antioxidant such as
17 hindered phenol, and one or more dispersants, one or more detergents, and
18 one or more wear inhibitors. Another embodiment of this invention may be
19 lubricating oil comprising one or more of the antioxidant systems of (his
20 invention. Another embodiment of this invention may be lubricating oil
21 comprising one or more of the additive formulations of this invention. These
22 antioxidant systems, additive formulations and lubricating oils may be
23 particulate useful in natural gas fueled engines.
24 Another embodin:ient of this invention may be a method to make a
25 lubricating oil comprising the antioxidant systems of this invention by
26 combining the components and mixing them together and heating at a
27 temperature sufficient to encourage mixing of the components, but not
28 sufficient to degrade the components. Another embodiment of this invention is
29 a method of using the lubricating oils of this invention to lubricate an engine
30 by contacting the engine with the lubricating oil of this invention. Another
31 embodiment of this invention is a method of using the lubricating oils of this
32 invention to lubricate a natural gas engine by contacting a natural gas engine
33 with the lubricating oil of this invention.

1
2 I. ANTIOXIDANT SYSTEM
3 One embodiment of the antioxidant system of this invention may
4 comprise sulfurized isobutylene. Lubricating oils of this invention may
5 comprise this additive system. Lubricating oil composing this antioxidant
6 system may comprise about 0,02 wt. % to about 2 wt. % sulfurized
7 isobutylene,
8 Another embodiment of the antioxidant system of this invention may
9 comprise the hindered phenols described herein and sulfurized isobutylene.
10 Lubricating oils of this invention may comprise this additive system. The
] 1 preferred concentration ratio of the sulfurized isobutylene to the hindered
12 phenol of this antioxidant system may be about 0.002 to about 2.5, more
13 preferred about 0,004 to about 1.13. A lubricating oil comprising this
J4 antioxidant system may comprise about 0.21 wt. % to about 6.50 wt. %, more
15 preferably about 0.42 wt. % to about 5.45 wt. % of an antioxidant system
16 comprising sulfurized isobutylene and one or more hindered phenols
17 described herein.
IS When wt. % is used herein it is refers to wt. % of lubricating oil unless
19 otherwise defined.
20
21 A. Sulfurized Isobutylene
22 Sulfurized isobutylene is known by those skilled in the art to be an
23 extreme pressure agent, effective in preventing wear in high pressure
24 environments such as gear lubrication. This invention is based on the finding
25 that when sulfurized isobutylene is used alone or in combination with
26 traditional antioxidants such as hindered phenols, there is an improvement in
27 oxidation, nitration and percent viscosity increase measurements. Using 2S sulfurized isobutylene in a lubricant for engines and for natural gas fueled

29 engines in particular is different than using sulfurized isobutylene as an
30 extreme pressure agent in lubricating oil for gear applications. Sulfurized
31 isobutylene used as an anti wear agent in gear applications is not typically
yi exposed to combustion gases and water, whereas sulfurized isobutylene used
33 as an antioxidant in lubricants for natural gas fueled engines or any engine

i may typically be exposed to combustion gases and water in the form of
2 condensation.
3 Sulfurized isobutylene comprises a long chain hydrocarbon that is
4 reacted with a various sulfur compounds that are incorporated into the chain.
5 This provides an oil soluble compound that is effective in providing extreme
6 pressure (EP) protection.
7 Sulfurized isobutylene fcr use in certain embodiments of this invention
8 may include one or more of sulfurized isobutylene such as
9 Mobilad C-100 and R.T. Vanderbilt Van lube SB. One embodiment of the

10 invention may be a lubricating oil that comprises less than about
11 2 Vift. % sulfurized isobutylene.
12 One embodiment of the lubricating oil of this invention may comprise
13 an antioxidant system comprising about 0.02 wt. % to about 2 wt. % sulfurized
14 isobutylene or preferably about 0.04 wt. % to about 1.75 wt. % sulfurized
15 isobutylene. Another embodiment of the lubricating oil of this invention may
16 comprise an antioxidant system comprising the hindered phenols described
17 herein and about 0.01 weight percent (wt. %) to about 0.5 wt. %, more
18 preferably from about 0.02 wt. % to about 0.45 vA. % sulfurized isobutylene.
19
20 B. Hindered Phenol
21 Embodiments of this invention may comprise hindered phenols. Liquid
22 hindered phenols are preferred. Preferred hindered phenols include one or
23 more hindered phenols having the general formula:
24
n
25 26 27 28
29 Wl - . - , ^ .
30 The lubricating oil of this invention may comprise about 0.10 wt. % to
31 about 3-0 wt. %, preferably from about 0.20 wt. % to about 2.50 wt. % of
32 one or more hindered phenols of the general formula (1).

1 A most preferred antioxidant of this invention is commercially available
2 from Ciba Specialty Chemicals at 540 White Plains Road, Tarrytown,
3 New York 10591 as IRGANOX L 135® or Compton Corporation at
4 199 Benson Road, Middlebury, CT 06749 as Naugard®PS-48.
5 IRGANOX L 135® and Naugard®PS-48 are liquid high molecular weight
6 phenol antioxidants of formula (1) above, wherein R is a mixture of C? to C9
7 alkyl groups. The lubricating oil of this invention may comprise about 0.10 v/t.
& % lo about 3.0 wt. %, preferably from about 0.20 wt. % to about 2.50 wt. % of
9 IRGANOX L 135c§)or Naugard®PS-48.
10 Embodiments of this invention may comprise butylated hydroxy
11 toluene (BHT). The lubricating oil of this invention may comprise about
12 0.10 wt. % to about 3.0 wt. % BHT and preferably about 0.20 wt. % to about
13 2.50 vrt.% BHT.
!4 The lubricating oil of this invention may comprise combined BHT and
15 other hindered phenols described herein. This combination may be present in
16 about 0.20 wt. % to about 6.00 wt. %, more preferably about 0.40 wt. % to
17 about 5.00 wt. % of the finished oil.
18
19 M. ADDITIVE FORMULATION
20 When incorporated in lubricating oil, certain embodiments of the
2t additive formulation of this invention may provide enhanced oxidation
22 inhibition, nitration inhibition, total base retention, reduction in acid formation
23 and reduction in percent viscosity increase. The additive formulation of this
24 invention may comprise one or more of the antioxidant systems described
25 herein,
26 Another embodiment of the additive formulation of this invention may
27 comprise butylated hydroxy toluene, sulfurized isobutylene, one or more
28 detergents, one or more dispersants, one or more wear inhibitors and one or
29 more of 3,5-di-t-butyl 4-hydroxy phenyl propionate and hindered phenols
30 having the general formula (1). Other traditional additives may be used.
31 Another embodiment of the additive formulation of this invention may
32 comprise sulfurized isobutylene, one or more detergents, one or more

1 dispersants and one or more wear inhibitors. Other traditional additives may
2 be used.
3 Another embodiment of the additive formulation of this invention may
4 comprise sulfurized isobutylene, one or more detergents, one or more
5 dispersants, one or more inhibitors and one or more of 3,5-di-t-buty(
6 4-hydroxy phenyl propionate and hindered phenols having the general
7 formula (1). Other traditional additives may be used.
8 The additive formulation of this invention may comprise diluent oil. It is
9 known in the art to add diluent oil to additive formulations and this is called
10 "trimming" the additive formulation. A preferred embodiment may be trimmed
11 with any diluent oil typically used in the industry. This diluent oil may be a
12 Group I, II, III, IV or V oil. A preferred amount of diluent oil may comprise
13 about 4.00 wn. %.
14
15 III. OTHER ADDITIVE COMPONENTS
16 The following additive components are examples of some of the
17 components that may be favorably employed in the present invention in
18 addition to the antioxidant system of this invention. These examples of
19 additives are provided to illustrate the present invention, but they are not
20 intended to limit it.
21
22 A. Detergent
23 Any detergents commonly used in lubricating oils may be used in this
24 invention. These detergents may or may not be overbased detergents or they
25 may be low, neutral, medium, or high overbased detergents. For example,
26 detergents of this invention may comprise sulfonates, salicylates and
27 phenates. Metal sulfonates, salicylates and phenates are preferred. When the
28 term metal is used with respect to sulfonates, salicylates and phenates herein,
29 it refers to calcium, magnesium, lithium, magnesium, potassium and barium.
30 The lubricating oil of this invention may comprise about 1.0 wt. % to
31 about 8.5 wt. %, preferably about 2 wt. % to about 6 wt. % of one or more
32 detergents.

1
2 B. Additional Antioxidants
3 If desired, additional antioxidants may be used. Other antioxidants may
4 reduce the tendency of mineral oils to deteriorate in service. In addition to the
5 antioxidant systems of this invention, the additive formulation may also
6 include but is not limited to such antioxidants as phenol type (phenolic)
7 oxidation inhibitors, such as 4,4'-methylene-bis{2,6-di-tert-butylphenol),
8 4,4'-bis(2,6-di-tert-butylphenol), 4,4'-bis(2-methyl-6-tert-butylphenol),
9 2,2'-methylene-bis(4-methyl-6-tert-butylphenol),

10 4,4'-butylidene-bis{3-methyl-6-tert-butylphenQl),
11 4,4'-isopropylidene-bis(2,6-di-tert-butylpheno)),
12 2,2'-methylene-bis(4-methyl-6-nonylphenol),
13 2,2'-isobutylidene-bis(4,6-dimethylphenol),
14 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol),
!5 2,6-di-tert-butyi-4-methy(phenol, 2,6-di-tert-bulyl-4-ethylphenol,
16 2,4-dimethyl-6-tert-butyl-phenol, 2,6-di-tert-l-dimethylamino-p-cresol,
17 2,6-di-tert-4-(N,N'-dimethylaminomethylphenol),
18 4,4'-thiobis(2-methyl-6-tert-butylphenoi),
19 2,2'-thiobis{4-methyl-6-tert-butyIphenol),
20 bis(3-methyl-4-hydraxy-5-tert-butylbenzyl)-sulfide, and
21 bis(3,5-di-tert-butyl-4-hydroxybenzyl). Diphenylamine-type oxidation inhibitors
22 include, but are not limited to, alkylated diphenylamine,
23 phenyl-.alpha.-naphthylamine, and alkylated-.alpha.-naphthylamine. Other
24 types of oxidation inhibitors include metal dithiocarbamate (e.g., zinc
25 dithiocarbamate), and methylenebis (dibutyldithiocarbamate).
26
27 C. Wear Inhibitors
28 Traditional wear inhibitors may be used in this invention. As their name
29 implies, these agents reduce wear of moving metallic parts. Examples of such
30 agents include, but are not limited to phosphates, phosphites, carbamates,
3! esters, sulfur containing compounds, and molybdenum complexes. The
32 finished lubricating oil of this invention may comprise one or more wear
33 inhibitors such metal dithiophospates and metal dithiocarbamates or mixtures

34 thereof. A preferred wear inhibitor for use in this invention comprises zinc
35 dithiophosphate. Lubricating oil of this invention may comprise about
36 0.2 wt. % to about 1.5 wt. % or preferably about 0.3 wt. % to about
37 0.8 wt. % of one or more wear inhibitors.
5
6 D. Rust Inhibitors {Anti-Rust Agents)
7 Nonionic poiyoxyethylene surface active agents: polyoxyethylene lauryi
H ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonyl phenyl
9 ether, polyoxyethylene octyl phenyl ether, polyoxyethylene octyl stearyl ether,
10 polyoxyethylene oleyl ether, poiyoxyethylene sorbitol monostearate,
n polyoxyethylene sorbitol mono-oleate, and polyethylene glycol mono-oleate
12 may be used.
13 Other compounds such as stearic acid and other fatty acids,
14 dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of heavy
!5 sulfonic acid, partial carboxylic acid ester of polyhydric alcohol, and
16 phosphoric ester may be used.
17
18 E. Demulsifiers
19 Addition product of alkylphenol and ethylene oxide, polyoxyethylene
20 alkyl ether, and polyoxyethylene sorbitan ester may be used.
21
22 F. Extreme Pressure Agents (EP Agents)
23 Zinc dialkyldithiophosphate (primary alkyl, secondary alkyl, and aryl
24 type), sulfurized oils, diphenyl sulfide, methyl trichlorostearate, chlorinated
25 naphthalene, fiuoroalkylpotysiloxane, and lead naphthenate may be used.
26
27 G. Friction Modifiers
28 Fatty alcohol, fatty acid, amine, borated ester, and other esters may be
29 used.
30
31 H. Multifunctional Additives
32 Sulfurized oxymolybdenum dithiocarbamate, sulfurized
33 oxymolybdenum organo phosphorodithioate. oxymolybdenum monoglyceride,

1 oxymolybdenum diethylate amide, amine-molybdenum complex compound,
2 and sulfur-containing molybdenum complex compound may be used.
3
4 I. Viscosity Index improvers
5 Polymethacrylate type polymers, ethylene-propylene copolymers,
6 styrene-isoprene copolymers, hydrated styrene-isoprene copolymers,
7 polyisobutyiene, and dispersant type viscosity index improvers may be used.
8
9 J. Pour Point Depressants
10 Polymethyl methacrylate may be used.
11
12 K. Foam Inhibitors
13 Alkyl methacrylate polymers and diethyl silicone polymers may be
14 used.
15
16 L. Dispersants
n A preferred embodiment of the lubricating oil of this invention may
15 comprise one or more nitrogen containing dispersants of the type generally
19 represented by succinimides (e.g., polyisobutyiene succinic acid/anhydride
20 {PIBSA)-polyamine having a PI BSA molecular weight of about 700 to
21 2500). The dispersants may be borated or non-borated, cashless or ash
22 containing. Lubricating oils of this invention may comprise about 1 wt. % to
23 about 8 vA. % or more preferably about 1.5 wt. % to about 6 vrt of one,or more
24 dispersants.
25 Preferred dispersants for this invention comprise one or more
26 dispersants having an average molecular weight (mw) of about 1000 to about
27 5000. Dispersants prepared from polyisobutyiene (RIB) having a mw of about
2S 1000 to about 5000 are such preferred dispersants.
29 A preferred dispersant of this invention may be one or more
30 succinimides. The term "succinimide" is understood in the art to include many
31 of the amide, imide, etc. species that are also formed by the reaction of a
32 succinic anhydride with an amine and is so used herein. The predominant
33 product, however, is succinimide and this term has been generally accepted

34 as meaning the product of a reaction of an alkenyl- or alkyl-substituted
35 succinic acid or anhydride with a polyamine. Alkenyl or alkyl succinimides are
36 disclosed in numerous references and are well known in the art. Certain
37 fundamental types of succinimides and related materials encompassed by the
38 term of art "succinimide" are taught in U.S. Pat. Nos. 2,992,708; 3,018,250;
39 3,018,291; 3.024,237; 3,100,673; 3,172,892; 3,219,666; 3.272,746;
40 3.361,673; r..381,022; 3,912,764; 4,234,435; 4,612,132; 4,747,965;
41 5.112,507; 5,241,003; 5,266,186; 5,286,799; 5,319,030; 5.334,321;
42 5,356,552; 5,716,912, the disclosures of which are hereby incorporated by
10 reference.
11 This invention may comprise one or more succinimides, which may be
12 either a mono or bis-succinimide. This invention may comprise lubricating oil
13 involving one or more succinimide dispersants that have or have not been
14 post treated.
15
16 IV. GROUP), II, III, IV AND V BASE OIL
17 Base Oil as used herein is defined as a base stock or blend of base
18 stocks. Base Stock as used herein is defined as a lubricant component that is
19 produced by a single manufacturer to the same specifications (independent of
20 feed source or manufacturers location that meets the same manufacturer's
21 specification and that is identified by a unique formula, product identification
22 number, or both. Base stocks may be manufactured using a variety of
23 different processes including but not limited to distillation, solvent refining,
24 hydrogen processing, ollgomerization, esterification, and rerefining. Rarefied
25 stock shall be substantially free from materials introduced through
26 manufacturing, contamination, or previous use. The base oil of this invention
27 may be any natural or synthetic lubricating base oil fraction particularly those
28 having a kinematic viscosity at 100 degrees Centigrade (C) and about
29 5 centistokes (cSt) to about 20 cSt, preferably about 7 cSt to about
30 16 cSt, more preferably about 9 cSt to about 15 cSt. Hydrocarbon synthetic
31 oils may include, for example, oils prepared from the polymerization of
32 ethylene, i.e., polyalphaolefin or PAG, or from hydrocarbon synthesis
33 procedures using carbon monoxide and hydrogen gases such as in a

34 Fisher-Tropsch process. A preferred base oil is one they comprises little, if
35 any, heavy fraction; e.g., little, if any, lube oil fraction of viscosity 20 cSt or
36 higher at 100 degrees C.
4 The base oil may be derived from natural lubricating oils, synthetic
5 lubricating oils or mixtures thereof. Suitable base oil includes base stocks
6 obtained by summarizations of synthetic wax and slack wax, as well as
7 hydrocrackste base stocks produced by hydrocracKing (rather than solvent
8 extracting) the aromatic and polar components of the crude. Suitable base oils
9 include those in API categories I II, III, and IV. Saturates levels and viscosity

10 indices for Group I, II and III base oils are listed in Table 1. Group IV base oils
11 are polyalphaolefins (PAO). Group V base oils include all other base oils not
12 included in Group I, II, III, or IV. Suitable base oils may include those in
13 API categories I, II, III, and IV as defined in API Publication 1509,
14 14'" Edition Addendum I, December 1998.
15
16
!7 IS
19
20 Natural lubricating oils may include animal oils, vegetable oils
21 (e.g., rapeseed oils, castor oils and lard oil), petroleum oils, mineral oils, and
22 oils derived from coal or shale.
23 Synthetic oils may include hydrocarbon oils and halo-substituted
24 hydrocarbon oils such as polymerized and inter-polymerized olefins,
25 alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl
26 sulfides, as well as their derivatives, analogues and homologues thereof, and

the like. Synthetic lubricating iris also include alkylated oxide polymers,
2 interpolymers, copolymers and derivatives thereof wherein the terminal
3 hydroxyl groups have been modified by esterification, etherification, etc.
4 Another suitable class of synthetic lubricating oils comprises the esters of
5 dicarboxyiic acids with a variety of alcohols. Esters useful as synthetic oils
6 also include those made from C5 to C12 monocarboxylic acids and polyols and
7 pothole ethers Tri-alkyl phosphate ester oils such as those exemplified by
8 tri-n-butyl phosphate and tri-iso-butyl phosphate are also suitable for use as
9 base oils.
10 Silicon-based oils {such as the play -, polyaryl-, polyalkoxy-, or
11 polyaryloxy-siloxane oils and silicate oils) comprise another useful class of
12 synthetic lubricating oils. Other synthetic lubricating oils include liquid esters
u of phosphorus-containing acids, polymeric tetrahydrofurans. polyalphaolefins,
14 and the like.
15 The base oil may be derived from unrefined, refined, redefined oils, or
16 mixtures thereof Unrefined oils are obtained directly from a natural source or
17 synthetic source (e.g., coal, shale, or tar sand bitumen) without further
18 purification or treatment. Examples of unrefined oils include a shale oil
19 obtained directly from a retorting operation, a petroleum oil obtained directly
20 from distillation, or an ester oil obtained directly from an esterification process,
21 each of which may then be used without further treatment. Refined oils are
22 similar to the unrefined oils except that refined oils have been treated in one
23 or more purification steps to improve one or more properties. Suitable ,
24 purification teciiniques include distillation, hydrocracking, hydretreating,
25 dew axing, solvent extraction, acid or base extraction, filtration, and
26 percolation, all of which are known to those skilled in the art. Redefined oils
27 are obtained by treating used oils in processes similar to those used to obtain
28 the refined oils. These redefined oils are also known as reclaimed or
29 reprocessed oils and often are additionally processed by techniques for
30 removal of spent additives and oil breakdown products.
31 Base oil derived from the hydroisomerization of wax may also be used,
32 either alone or in combination with the aforesaid natural and/or synthetic base

1 oi). Such wax isomerate oil is produced by the hydroisomerization of natural or
2 synthetic waxes or mixtures thereof over a hydroisomerization catalyst.
3 It is preferred to use a major amount of base oil in the lubricating oil of
4 this invention. A preferred range of base oil for this invention may be about
5 80 vA. % to about 97 wt. % of the lubricating oil. {When wt. % is used herein, it
6 is referring to wt. % of the lubricating oil unless otherwise specified.) A more
7 preferred embodiment of this invention may comprised an amount of basso oil
s that comprises about 85 vrt. % to about 95 wt. % of the lubricating oil.
9
10 V. FINISHED LUBRICATING OIL COMPRISING THE ADDITIVE
11 FORMULATION
12
13 The following embodiments of finished lubricating oils are illustrative
14 only. The invention is not limited to these embodiments.
15 One embodiment of the lubricating oil of this invention may comprise
16 lubricating oil, the hindered phenols described herein and sulfurized
17 isobutylene. The components of the antioxidant systems of this invention and
18 other additives traditionally used in the industry may be incorporated in
19 lubricating oil in any manor either individually or In any combination.
20 One embodiment of the lubricating oil of this invention may comprise
21 about 0.21 wt. % to about 6.5 wt. %, more preferably about 0.42wt. % to
22 about 5.45 wt. % of one or more of the antioxidant systems of this invention
23 comprising the hindered phenols described herein and sulfurized isobutyiene.
24 Other additives traditionally used in the art may be included in the finished
25 lubricating oil of this invention.
26 One embodiment of the lubricating oil of this invention comprises a
27 major amount of one or more base oils, about 1 wt. % to about 8 vA. % of one
28 or more dispersants; about 1 wt. % to about 8,5 wt. % of one or more
29 detergents, about 0.2 wt. % to about 1.25 wt. % of one or more wear
30 inhibitors, about 0.01 wt. % to about 0.5 wt. % sulfurized isobutyiene, and
31 about 0.2 wt. % to about 6 vrt. % of one or more of the hindered phenols
32 described herein. This embodiment may be prepared by combining the
33 components with agitation until all components are mixed. The ingredients
34 may be combined in any order and at a temperature sufficient to blend the

35 components but not high enough to degrade the components. A temperature
36 of about 120 degrees F {approximately 49 degrees C) to about 160 degrees F
37 (approximately 71 degrees C} may be used. It does not matter whether the
38 components are heated before after or during combining them.
5 One embodiment of the lubricating oil of this invention comprises a
6 major amount of one or more base oils, about 1.25 wt. % to about 6 wt. % of
7 one or more dispersants; about 2 wt. % to about 6 wt. % of one or more
8 detergents, about 0.3 wt. % to about 0.8 wt. % of one or more wear inhibitors,
9 about 0.02 wt. % to about 0.45 wt. % sulfurized isobutylene, and about

10 0.4 wt. % to about 5 wt. % of one or more of the hindered phenols described
11 herein. This embodiment may be prepared by combining the components with
12 agitation until all components are mixed. The ingredients may be combined in
13 any order and at a temperature sufficient to blend the components but not
14 high enough to degrade the components. A temperature of about
15 120 degrees F (approximately 49 degrees C) to about 160 degrees F
!6 (approximately 71 degrees C) may be used. It does not matter whether the
17 components are heated before after or during combining them.
IS One embodiment of the lubricating oil of this invention comprises
19 lubricating oil comprising a major amount of one or more base oils, about
20 1 wt. % to about 8 wt. % of one or more dispersants, about 1 wt. % to about
21 8.5 wt. % of one or more detergents, about 0.2 wt. % to about 1.25 wt. % of
22 one or more wear inhibitors, and about 0.02 wt. % to about 2 wt. % sulfurized
23 isobutylene. This embodiment may be prepared by combining the
24 components with agitation until all components are mixed. The ingredients
25 may be combined in any order and at a temperature sufficient to blend the
26 components but not high enough to degrade the components. A temperature
27 of about 120 degrees F (approximately 49 degrees C) to about 160 degrees
28 F (approximately 71 degrees C) may be used. It does not matter whether the
29 components are heated before after or during combining them.
30 One embodiment of the lubricating oil of this invention comprises
31 lubricating oil comprising a major amount of one or more base oils, about
32 1.25 wt. % to about 6 wt. % of one or more dispersants, about 2 wt. % to
33 about 6 wt. % of one or more detergents, about 0.3 wt. % to about

34 0.8 wt. %of one or more wear inhibitors, and about 0.04 wt. % to about
35 1.75 wt. % sulfurized isobutylene. Tliis embodiment may be prepared by
36 combining the components with agitation until all components are mixed. The
37 ingredients may be combined in any order and at a temperature sufficient to
38 blend the components but not high enough to degrade the components. A
39 temperature of about 120 degrees F (approximately 49 degrees C) to about
40 160 degrees F {approximately 71 degrees C) may be used. It does not matter
41 whether the components are heated before after or during combining them.
9 One embodiment of the lubricating oil of this invention may have a
10 Total Base Number (TBN) of about 2.15 milligrams Potassium Hydroxide
11 per gram of sample (mg KOH/gr) to about 8.88 mg KOH/gr. A more preferable
12 embodiment would have a TBN from about 3.00 mg KOH/gr to about
!3 8.00 mg KOH/gr. Unless otherwise specified, TBN, as used herein, is
14 determined by using the method ASTM D2896.
15 Another embodiment of this invention may comprise a method of
16 lubricating engines comprising contacting one or more engines with any
17 embodiment of the lubricating oil of this invention.
18 Another embodiment of this invention comprises a method of
19 lubricating natural gas engines comprising contacting one or more natural gas
20 engines with any embodiment of the lubricating oil of this invention.
21 Another embodiment of this invention comprises a method of
22 lubricating engines comprising lubricating one or more engines with any
23 embodiment of the lubricating oil of this invention.
24 Another embodiment of this invention comprises a method of
25 lubricating natural gas engines comprising lubricating one or more natural gas
26 engines with any embodiment of the lubricating oil of this invention.
27 Another embodiment of this invention comprises combining the
28 components of any embodiment of lubricating oil of this invention. This
29 embodiment may be accomplished by combining the components with
30 agitation until all components are mixed. The ingredients may be combined in
31 any order and at a temperature sufficient to blend the components but not
32 high enough to degrade the components, A temperature of about
33 120 degrees F(approximately 49 degrees C) to about 160 degrees F

34 (approximately 71 degrees C) may be used. It does not matter whether the
35 components are heated before after or during combining them.
3
4 VI. LUBRICATING OIL FOR NATURAL GAS FUELED ENGINES
5 There is a difference in the lubricating oil requirements for natural gas
6 fueled engines and engines that are fueled by liquid hydrocarbon fuels. The
7 combustion of liquid hydrocarbon fuels such as diesel fuel often results in a
8 small amount of incomplete combustion (e.g., exhaust particulates). In a liquid
9 hydrocarbon fueled engine, these incombustibles provide a small but critical

10 degree of lubrication to the exhaust valve/seat interface, thereby ensuring the
11 durability of both cylinder heads and valves. The combustion of natural gas
12 fuel is often very complete, with virtually no incombustible materials,
13 Therefore, the durability of the cylinder head and valve is controlled by the
14 ash content and other properties of the lubricating oil and its consumption
15 rate. There are no incombustible materials to aid in lubrication to the exhaust
16 valve/seat interface in a natural gas fueled engine. Natural gas fueled engines
17 burn fuel that is introduced to the combustion chamber in the gaseous phase.
18 This has a significant affect on the intake and exhaust valves because there is
19 no fuel-derived lubricant for the valves like liquid droplets or soot.
20 Consequently, gas engines are solely dependent on the lubricant ash to
21 provide lubricant between the hot valve face and its mating seat. Too little ash
22 or the wrong type can accelerate valve and seat wear, while too much ash
23 may lead to valve guttering and subsequent valve torching. Too much ash can
24 also lead to detonation from combustion chamber deposits. Consequently,
25 gas engine builders frequently specify a narrow ash range that they have
26 learned provides the optimum performance. Since most gas is low in sulfur,
27 excess ash is generally not needed to address alkalinity requirements, and
28 ash levels are largely optimized around the needs of the valves. There may
29 be exceptions to this in cases where sour gas or landfill gas is used.
30 Natural gas fueled engine lubricating oils are classified according to
3! their ash content. Unless otherwise specified, ash contents discussed herein
32 were determined by ASTM D874. The lubricant ash acts as a solid lubricant to
33 protect the valve/seat interface in place of naturally occurring exhaust

! particles in a hydrocarbon fueled engine. The oil industry has accepted
2 guidelines that classify natural gas fueled engine lubricating oil according to
3 their ash level. The classifications of natural gas fueled engine lubricating oil
4 according to their ash levels are presented in Table 2.

10 The ash level of lubricating oil is often determined by its formulation
11 components. Metal-containing detergents (e.g., barium, calcium) and
i2 metallic-containing wear inhibitors contribute to the ash level of lubricating
13 oils. For correct engine operation, gas engine manufacturers define lubricating
14 oil ash requirements as part of the lubricating oil specifications. For example,
15 manufacturers of 2-cycle engines often require natural gas engine lubricating

16 oil to be Ash less to minimize the extent of harmful deposits that form on the
17 piston and combustion chamber area. Manufacturers of 4-cycle engines often
18 require natural gas engine lubricating oils to be Low, Medium or High Ash
19 levels, refer to Table 2, to provide the correct balance of engine cleanliness
20 and durability of the cylinder head and valves. Running the engine with
21 lubricating oil with too low an ash level will likely result in shortened life for the
22 valves or cylinder head. Running the engine with lubricating oil having too
23 high an ash level will likely cause excessive deposits in the combustion
24 chamber and upper piston area.
25 The degree of nitration of the lubricating oil may vary significantly
26 depending on the engine design and operating conditions. Lean burn engines
27 produce less NOx than their stoichiometric counterparts, so they tend to
28 nitrate the oils less. Some operators may richen the air/fuel mixture on natural
29 gas fueled engines to increase power output and consequently increase oil
30 nitration levels. Lubricating oils with good nitration resistance are required in
31 most natural gas engine installations hearse the lubricating oil may be used

32 to lubricate a number of engines including stoichiometric and lean-burn
33 models.
3 This invention will be further illustrated by the following examples that set
4 forth particularly preferred embodiments. While the examples are provided to
5 illustrate this invention, they are not intended to limit it.
6
7 EXAMPLES
8 These examples describe experiments performed using Samples A
9 through L. Multiple experiments were performed in each example using a
10 variety of detergents including but not limited to sulfonates, phonate and
31 calculate detergents; succinimide dispersants; and zinc dithiophosphate wear
12 inhibitors. The examples are explained using the terms detergent, dispersant
13 and wear inhibitor because no significant difference was found when these
14 components were varied.
15 Sample A was prepared by combining about 0.757 wt. % 3,5-di-t-butyl
16 4-hydroxy phenyl propionate, about 3.3 wt. % dispersant, about
17 3.0 vrt. % detergent, about 1.0 wt. % butylated hydroxy toluene, about
18 0.38 wt. % wear inhibitor, about 5 ppm foam inhibitor and Group I base oil
19 with agitation until all components were mixed. The ingredients were
20 combined at a temperature sufficient to blend the components but not high
21 enough to degrade the components. A temperature of about 140 degrees
22 Farenheit (approximately 60 degrees Celsius) was used.
23 Sample B was prepared by combining about 0.693 wt. % 3,5-di,-t-butyl
24 4-hydroxy phenyl propionate, about 3.3 wt. % dispersant, about
25 3.0 wt. % detergent, about 1.0 wt. % butylated hydroxy toluene, about
26 0.38 wt. % wear inhibitor, about 0.08 wt. % sulfurized isobutylene, about
27 5 ppm foam inhibitor and Group I base oil with agitation until all components
28 were mixed. The ingredients were combined at a temperature sufficient to
29 blend the components but not high enough to degrade the components. A
30 temperature of about 140 degrees F (approximately 60 degrees C)was used.
31 Sample C was prepared by combining about 0.629 wt. % 3,5-di-t-butyl
32 4-hydroxy phenyl propionate, about 3.3 wt. % dispersant, about
33 3.0 wt. % detergent, about 1.0 vA. % butylated hydroxy toluene, about

34 0.38 wt. % wear inhibitor, about 0.16 wt. % sulfurized isobutylene, about
35 5 ppm foam inhibitor and Group I base oil with agitation until all components
36 were mixed. The ingredients were combined at a temperature sufficient to
37 blend the components but not high enough to degrade the components. A
38 temperature of about 140 degrees F (approximately 60 degrees C) was used.
6 Sample D was prepared by combining about 0,56 wt. % 3,5-di-t-butyl
7 4-hydroxy phenyl propionate, about 3,3 wt. % dispersant, about
8 3.0 wt. % detergent, about 1.0 wt. % butylated hydroxy toluene, about
9 0.38 wt. % wear inhibitor, about 0.25 wt. % sulfurized isobutylene, about
io 5 ppm foam inhibitor and Group I base oil with agitation until all components
11 were mixed. The ingredients were combined at a temperature sufficient to
12 blend the components but not high enough to degrade the components. A
13 temperature of about 140 degrees F (approximately 60 degrees C) was used.
14 Sample E was prepared by combining about 0.674 wt. % 3,5-di'l-butyl
15 4-hydroxy phenyl propionate, about 3.3 wt. % dispersant, about
16 3.0 wt. % detergent, about 1.0 wt. % butylated hydroxy toluene, about
17 0.38 wt. % wear inhibitor, about 0.08 wt. % sulfurized isobutylene, about
18 5 ppm foam inhibitor and Group I base oil with agitation until all components
19 were mixed. The ingredients were combined at a temperature sufficient to
20 blend the components but not high enough to degrade the components. A
21 temperature of about 140 degrees F (approximately 60 degrees C) was used.
22 Sample F was prepared by combining about 0.592 wt. % 3,5-di-t-butyl
23 4-hydroxy phenyl propionate, about 3.3 wt. % dispersant, about
24 3.0 wt. % detergent, about 1.0 wt. % butylated hydroxy toluene, about
25 0.38 wt. % wear inhibitor, about 0.16 wt. % sulfurized isobutylene, about
26 5 ppm foam inhibitor and Group I base oil with agitation until all components
27 were mixed. The ingredients were combined at a temperature sufficient to
28 blend the components but not high enough to degrade the components. A
29 temperature of about 140 degrees F (approximately 60 degrees C) was used.
30 Sample G was prepared by combining about 0.499 wt. % 3,5-di't-butyl
31 4-hydroxy phenyl propionate, about 3.3 wt. % dispersant, about
32 3.0 wt. % detergent, about 1.0 wt. % butylated hydroxy toluene, about
33 0,38 wt. % wear inhibitor, about 0.25 wt, % sulfurized isobutylene, about

34 5 ppm foam inhibitor and Group 1 base oil with agitation until all components
35 are mixed. The ingredients were combined at a temperature sufficient to blend
36 the components but not high enough to degrade the components. A
37 temperature of about 140 degrees F (approximately 60 degrees C) was used.
5 Sample H was prepared by using OLOA 1255, commercially available
6 from Chevron Ornate Company in Houston, Texas. The OLOA 1255 was
7 mixed with Group 1 base oil under typical blending conditions of about
8 140 degrees F (approximately 60 degrees C) with agitation until all
9 components were thoroughly mixed. As explained in U.S. Pat. No, 5,726,133,

10 OLOA 1255 is one of the most widely sold gas engine oil additive packages
11 and lubricating oil comprising OLOA 1255 represents a "benchmark standard"
12 against which other formulations useful as engine oils may be measured.
13 Sample I was prepared by combining about 2 vA. % sulfurized
14 isobutylene, about 6.61 wt. % dispersant, detergent, wear inhibitor and foam
!5 inhibitor package and Group I base oi! and agitating until a\\ components were
16 mixed. The ingredients were combined at a temperature sufficient to blend the
17 components but not high enough to degrade the components. A temperature
15 of about 140 degrees F (approximately 60 degrees C) was used.
19 Sample J was prepared by combining about 2 wt. % sulfurized
20 isobutylene, about 6.61 wt. % of an additive package comprising dispersant,
21 detergent, wear inhibitor and foam inhibitor with Group !l base oil and
22 agitating until all components were mixed. The ingredients were combined at
23 a temperature sufficient to blend the components but not high enough to
24 degrade the components. A temperature of about 140 degrees F
25 (approximately 60 degrees C) was used.
26 Sample K was prepared by combining about 1.0 wt. % butylated
27 hydroxy toluene, about 6,61 wt. % of an additive package comprising
28 dispersant, detergent, wear inhibitor and foam inhibitor with Group I base oil
29 and agitating until all components were mixed. The ingredients were
30 combined at a temperature sufficient to blend the components but not high
31 enough to degrade the components. A temperature of about 140 degrees F
32 (approximately 60 degrees C) was used.

i Sample L was prepared by combining about 1.0 wt. % butylated
2 liydroxy toluene and about 6.61 wt. % of an additive package comprising
3 dispersant, detergent, wear inhibitor and foam inhibitor with Group II base oil
4 and agitating until all components were mixed. The ingredients were
5 combined at a temperature sufficient to blend the components but not high
6 enough to degrade the components. A temperature of about 140 degrees F
7 (approximately 60 degrees C) was used.
8
9 EXAMPLE 1
10 The Oxidation-Nitration and
11 Viscosity Increase Resistance Test
12
13 The Oxidation-Nitration and Viscosity Increase Resistance bench test
14 demonstrates the capacity of lubricating oil to resist oxidation, nitration and
15 viscosity increase. This test is a tool to help determine the performance of oils
16 as they relate to the actual service of lubricating engines that use natural gas as
17 a fuel source. The level of oxidation and nitration of oil, may also be compared
18 by monitoring the viscosity increase of the oil. The lower the values for
19 oxidation, nitration and viscosity increase at the end the test, the more superior
20 the product's performance. The Oxidation-Nitration and Viscosity Increase
21 Resistance bench test was designed to simulate Caterpillar 3500 series engine
22 conditions as related to actual field performance of the Caterpillar 3516 model.
23 Oxidation-Nitration and Viscosity Increase Resistance tests were performed on
24 Samples A through G. The samples were placed in a heated glassware bath
25 and subjected to calibrated levels of nitrous oxide gas over a specific period of
26 time. The tests were run on each sample in duplicate and the results are an
27 average of the two runs. The samples were evaluated using differential infra
28 red spectroscopy before placing them in the heated glassware bath to
29 determine a base line for each sample. The samples were re-evaluated at the
30 end of testing period. The differential between the base line data, absorbance
31 units at 5.8 and 6.1 microns, and the data taken at the end of test cycle
32 provides an indication of the oxidation-nitration resistance of the samples.
33 Differential infra red spectroscopy measures the amount of light that is
34 absorbed by an oil sample and provides a unit of measure called an

1 absorbance unit. DIR (Differential Infrared) spectra was determined by
2 subtracting the fresh oil spectra from the used oil spectra to observe changes
3 that have occurred due to oxidation, nitration, fuel dilution, soot accumulation,
4 and or contamination. Typically a 0,1 millimeter (mm) cell is used, however an
5 ATR crystal setup may be used after determining its associated path length. If
6 the instrument does not have software that determines path length, the path
7 length may be back calculated by measuring oxidation with a calibrated
8 0.1 mm cell. The variation between ATR and vertical cell measurements is
9 minimal if restricted to the narrow area of oxidation and nitration (-1725 to
10 1630 cm'}.
11 DIR Oxidation was measured from peak maximum at-1715 ± 5 cm"' to
12 the spectra baseline (in units of absorbance).
13 DIR Nitration was measured from peak maximum at -1630 ± 1 cm"' to
14 peak baseline (in units of absorbance).


6 Oxidation (&/or Nitration) Number Reported (abs/cm) = peal 7 absorbance divided by path length in cm'^ (report in whole numbers)
8 During the Oxidation-Resistance Bench Test, the viscosity increases of
9 the samples were measured at lOCC by ASTM D 445. The viscosity increase
10 is a percentage that compares the initial "fresh" kinematic viscosity with the end
i 1 of test "used" oil kinematic viscosity. The formula to calculate for % viscosity
12 difference is:
13
14 % Viscosity difference = (Sample (x) ^ia, - Sample (x) ,,r^]l Sample (x) wiai x 100 %
15
16 Oxidation levels of 5.8 microns and Nitration levels of 6.1 microns were
17 used as peak height comparisons.
IS
19 (a) Comparison of Samples A, B, C, D, E, F, G
20 Measurements are reported on a relative measurement basis so that
21 large results or values represent greater levels of oxidation-nitration and
22 viscosity increase resistance. Lower numbers represent shorter oil life.

1 Sample A was used as a reference oil and the results in the Tables 4-6 were
2 reported as a ratio in the first row of each table. This ratio was calculated by
3 dividing measurements for Sample A by the measurements taken using the
4 sample being compared to Sample A. The second row of each table displays
5 the percent difference between the reference Sample A and the samples being
6 compared to Sample A. The larger the percentage difference between
7 Sample A and the other samples, the better performing the sample in respect to
8 parameter being compared. Sample A was the reference sample for the results
9 reported in Table 4-6. The formula to calculate percentage difference of the
10 ratios compared to Sample A for Tables 4-6 is:



9
10 The results in Table 5 indicate improved performance of
11 Samples B through G over the reference sample A. The improvement ranged
12 from 2 % to 47 % over the reference Sample A in nitration resistance. Again,
13 Sample E performed better with respect to nitration resistance than all the
14 other amoles tested.
26 The results in Table 6 indicate that Samples B through G performed
27 better than reference Sample A. The improvement ranged from 2 % to
28 41 % over the reference sample in viscosity increase resistance.
29 Sample E performance was better than the reference sample with
30 respect to oxidation, nitration and viscosity increase. Sample E performed
31 better than all the samples tested with respect to minimizing the levels of

32 oxidation, nitration and viscosity increase. These tests quantify a lubricating
33 oil's resistance to oxidation, nitration and the resultant viscosity increase and

34 are used to determine whether samples are good candidates for extending
35 the life of lubricating oil particularly those lubricating oils for use in natural gas
36 fueled engines. Absorbing oxygen and nitrogen and the resultant viscosity
37 increase associated with absorbing oxygen and nitrogen are undesirable for
38 lubricating oil particularly lubricating oils for use in natural gas fueled engines.
6
7 (b) Comparison of Samples I and K
8 The Oxidation-Nitration and Viscosity Increase Resistance bench test
9 demonstrates the capacity of lubricating oil to resist oxidation, nitration and
10 viscosity increase. The Oxidation-Nitration and Viscosity Increase Resistance
11 tests described in Example 1 were performed on Samples I and K.
12 Measurements are reported on a relative measurement basis so that
13 large results or values represent greater levels of oxidation-nitration and
14 viscosity increase resistance. Lower numbers represent shorter oil life,
15 Sample K was used as a reference oil and the results in the Tables 7-9 were
16 reported as a ratio in the first row of each table. This ratio was calculated by
17 dividing measurements for Sample K by the measurements taken using the
18 sample being compared to Sample K. The second row of each table displays
19 the percent difference between the reference Sample K and Sample I being
20 compared to Sample I. The larger the percentage difference between
21 Sample K and Sample I, the better performing the sample in respect to
22 parameter being compared. Sample K was the reference sample for the results
23 reported in Table 7-9. The formula to calculate percentage difference of the
24 ratios compared to Sample K for Tables 7 - 9 is:
25
26 % difference = (Sample (x) - Sample K)/Sample (x) x 100 %
27



an
lie, A
10 The results presented in Table 9 indicate that Sample I exhibited a
11 42 % improvement in viscosity increase resistance over the reference
12 Sample K.
13 Sample I performance was better than the reference sample with
14 respect to oxidation, nitration and viscosity increase. Sample i performed
15 better than Sample K tested with respect to minimizing the levels of oxidation,
16 nitration and viscosity increase.
17
18 (c) Comparison of Samples J and L
19 The Oxidation-Nitration and Viscosity Increase Resistance bench test
20 demonstrates the capacity of lubricating oil to resist oxidation, nitration and
21 viscosity increase. This test is the same as described in

22 Example 1. Oxidation-Nitration and Viscosity Increase Resistance tests were
23 performed on Samples J and L, The test was run and analyzed as described in

24 Example 1. Samples J and L were tested in the test described in
25 Example 1. The oxidation and nitration of the samples were analyzed using

26 differential IR as described in Example 1. Viscosity Increase of the samples
27 was monitored by using the Viscosity Increase test described in Example 1.
28 Measurements are reported on a relative measurement basis so that
29 large results or values represent greater levels of oxidation-nitration and
30 viscosity increase resistance. Lower numbers represent shorter oil life.
31 Sample L was used as a reference oil and the results in the Tables 10-12

32 were reported as a ratio in the first row of each table. This ratio was calculated
33 by dividing measurements for Sample L by the measurements taken using the

1 sample being compared to Sample L. The second raw of each table displays
2 the percent difference between the reference Sample L and Sample J being
3 compared to Sample J, Tlie larger the percentage difference between
4 Sample L and Sample J, the better performing the sample in respect to

5 parameter being compared. Sample L was the reference sample for the results
6 reported in Table 10 - 12. The formula to calculate percentage difference of the
7 ratios compared to Sample L for Tables 10 -12 Is:
s
9 % difference = (Sample (x) - Sample lySample (x) x 100 %



10
11 The results presented in Table 12 indicate that Sample J exhibited a
12 70 % improvement in viscosity increase resistance over the reference
13 Sample L.
14 Sample J performance was better than the reference Sample L with
15 respect to oxidation, nitration and viscosity increase.
16 These tests quantify a lubricating oil's resistance to oxidation, nitration
17 and the resultant viscosity increase and are used to determine whether
18 samples are good candidates for extending the life of lubricating oil
19 particularly those lubricating oils for use in natural gas fueled engines.
20 Absorbing oxygen and nitrogen and the resultant viscosity increase
21 associated with absorbing oxygen and nitrogen are undesirable for lubricating
22 oil particularly lubricating oils for use in natural gas fueled engines.
23
24 EXAMPLE 2
25 Comparing Samples E and H
26 Because the Caterpillar 3500 series natural gas fueled engines are one
27 of the most commonly used and one of the most severe engines with respect
28 to oil life, they were used as a tool to determine the life of lubricating oil.
29 These tests were run in the same Caterpillar 3512 engine to minimize the
30 amount of variables that are introduced in the testing environment. Oil life as
31 used herein is the length of time it takes for a lubricating oil to reach
32 Caterpillar's condemning limits for natural gas fueled engine lubricating oil. At
33 the time of testing the Caterpillar limits are presented in Table 13.


5 Both samples were run in the Caterpillar 3512 until the condemning
6 limits were exceeded. The oxidation and nitration of the samples were
7 analyzed using differential IR as described in Example 1. Viscosity Increase of
8 the samples was monitored. The Viscosity Increase analysis is described in
9 Example 1. Sample E exhibited better performance with respect to oxidation,
10 nitration and viscosity increase than Sample H. Total Base Number (TBN) and
11 Total Acid Number (TAN) analyses were also performed. TBN refers to the
12 amount of base equivalent to milligrams of KOH in one gram of sample. Thus,

13 higher TBN numbers reflect more alkaline products, and therefore a greater
14 alkalinity reserve. The TBN of a sample may be determined by
15 ASTM Test No. D2896. TAN refers to the amount of acid equivalent to
!6 milligrams of Potassium Hydroxide (KOH) in 1 gram of sample. TAN was
17 determined by the procedure described in ASTM D664.
18 Samples E and H were tested separately by using each one as a
19 lubricant in the same Caterpillar 3512 natural gas fueled engine for a total
20 time of over 5 months. The oxidation and nitration of the samples were
21 analyzed using differential IR as described in Example 1. Viscosity Increase of
22 each sample was monitored by using the Viscosity Increase test described in

23 Example 1. Total Base Number (TBN) and Total Acid Number (TAN) analyses
24 were also performed as described above.
25 Sample E oil life performance was better than that of Sample H. Both
26 samples were formulated in Group I base oil. TBN and TAN performance are
27 parameters that are typically used to decide when to condemn lubricating oil.
28 Sample E had an increased oil life of 75 % and 79 %, respectively, when
29 compared to Sample H.


9 These results demonstrate that the lubricating oil compositions
10 comprising the antioxidant system of this invention show high resistance to
1! oxidation, nitration and viscosity increase.
12 While the invention has been described in terms of various
13 embodiments, the skilled artisan will! appreciate that various modifications,
14 substitutions, omissions and changes may be made without departing from
15 the spirit thereof.


I WHAT IS CLAIMED IS:
2
3 1. An antioxidant system comprising;
4
5 a. sulfurized isobutylene and
6
7 b. one or more hindered phenols.
8
9 2. An antioxidant system of Claim 1 wherein the hindered phenols
10 comprise butylated hydroxy toluene and benzenepropanoic acid, 3,5-
11 bis (1,1-dimethyl-ethyl)-4-hydroxy-, C7-C9 branched alkyl esters.
12
13 3. An antioxidant system of Claim 1 wherein the hindered phenols
14 comprise butylated hydroxy toluene.
15
16 4. An antioxidant system of Claim 1 wherein one or more hindered
17 phenols have the genera! formula:
IS
!9 20 21 22
23 wherein R is a C7-C9 alkyl group.
24
25 5. An antioxidant system of Claim 4, wherein the antioxidant system
26 further comprises butylated hydroxy toluene.
27
2S 6. Lubricating oil compnsing a base oil and the antioxidant system of
29 Claim 1.
30
31 7. Lubricating oil comprising a base oil and the antioxidant system of
32 Claim 2.
33

1 8. Lubricating oil comprising a base oil and the antioxidant system of
2 Claim 3.
3
4 9, Lubricating oil comprising a base oil and the antioxidant system of
5 Claim 4.
6
7 10. A method of lubricating engines comprising contacting the lubricating
8 oil of Claim 6 with one or more engines.
9
10 11. A method of lubricating engines comprising lubricating one or more
11 engines with the lubricating oil of Claim 6.
12
13 12. A method of lubricating engines comprising contacting one or more
14 engines with the lubricating oil of Claim 8.
15
16 13. A method of lubricating engines comprising contacting one or more
17 engines with lubricating oil of Claim 9.
18
19 14. A method of Claim 13 wherein the engine is a natural gas fueled
20 engine,
2i
22 15. Lubricating oil comprising:
23
24 about 1 wt. % to about 8 wt. % of one or more dispersants;
25
26 about 1 wt. % to about 8.5 wt. % of one or more detergents;
27
28 about 0.2 wt. % to about 1.5 wt. % of one or more wear inhibitors;
29
30 about 0.01 wt. % to about 0.5 wt. % sulfurized isobutylene;
31
32 about 0.1 wt. % to about 3 wt. % butyiated hydroxy toluene;
33

1 and about 0,1 wt. % to about 3 wt. % benzenepropanoic acid, 3,5-bis
2 (1,1-dimethyl-ethyl)-4-hydroxy-, C1-C9 branched alkyl esters,
3
4 16. A method of lubricating engines comprising lubricating one or more
5 engines with the lubricating oil of Claim 15.
6
7 17. A method of making the lubricating oil of Claim 15 comprising
8 combining;
9
10 about 1 wt. % to about 8 wt. % of one or more dispersants;
li
12 about 1 wt. % to about 8.5 wt. % of one or more detergents;
13
14 about 0.2 wt. % to about 1.5 wt. % of one or more wear inhibitors;
15
16 about 0.01 wt. % to about 0.5 wt. % sulfurized isobutylene;
17
15 about 0.1 w!. % to about 3 wt. % butylated hydroxy toluene; and
19
20 about 0.1 wt. % toabout 3 wt. % benzenepropanoic acid, 3,5-bis (1,1-
21 dimethy!-ethyl)-4-hydroxy-, Cr-C9 branched alkyl esters in any order.
22
■23 18. Lubricating oil comprising:
24
25 a major amount of one or more base oils;
26
27 about 1.25 wt. % to about 6 wt. % of one or more dispersants;
28
29 about 2 wt. % to about 6 wt. % of one or more detergents;
30
31 about 0.3 wt. % to about 0.8 wt. % of one or more wear inhibitors;
32
33 about 0.02 wt. % to about 0,45 wt. % sulfurized isobutylene;

1
2 about 0.20 wt. % to about 2.5 wt. % butylated hydroxy toluene; and
3
4 about 0.20 wt. % to about 2.5 wt. % benzenepropanoic acid, 3,5-bis
5 (1,1-dimethyl-ethyl)-4-hydroxy-, C1-C9 branched alkyl esters.
6
7 19. A method of lubricating engines comprising contacting one or more
8 engines with the lubricating oil of Claim 18.
9
10 20. A method of making the lubricating oi! of Claim 18 comprising
11 combining:
12 a major amount of one or more base oils;
13
14 about 1.25 wt. % to about 6 wt. % of one or more dispersants;
15
16 about 2 wt. % to about 6 wt. % of one or more detergents;
17
18 about 0.3 wt. % to about 0.8 wt. % of one or more wear inhibitors;
19
20 about 0.02 wt. % to about 0.45 wt. % sulfurized isobutylene;
21
22 about 0.20 wt. % to about 2.5 wt. % butylated hydroxy toluene; and
23
24 about 0.20 wt. % to about 2.5 wt. % benzenepropanoic acid, 3,5-bis
25 (1,1-dimethyl-ethyl)-4-hydroxy-, C7-C9 branched alkyl esters in any
26 order.
27
28 21. Lubricating oil for use in engines comprising sulfuhzed isobutylene.
29
30 22. Method of lubricating natural gas engines comprising contacting the
31 lubricating oil of Claim 21 with one or more natural gas engines.
32 33

i 23. Lubricating oil comprising:
2
3 about 0.02 wt, % to about 2 wt. % sulfurized isobutylene;
4
5 about 1 wt. % to about 8 wt. % of one or more dispersants;
6
7 about 1 wt. % to about 8.5 wt. % of one or more of phenates,
8 salyciiates and sulfonates;
9
10 about 0.2 wt. % to about 1.5 wt. % of one or more wear inhibitors; and
11 oneor more of Group 1,11, III and iV base oil.
!2
13 24. A method of making the lubricating oil of Claim 23 comprising blending
14 about 0.02 wt. % to about 2 wt. % sulfurized isobutylene;
15
16 about 1 wt. % to about 8 wt. % of one or more dispersants:
17
18 about 1 wt. % to about 8.5 wt. % of one or more of phenates,
19 salyciiates and sulfonates;
20
21 about 0.2 wt. %to about 1.5 wt. % of one or more wear inhibitors; and
22
23 oneor more of Group I, II, III and IV base oil in any order with agitation
24 and at a temperature sufficient to blend the components but not high
25 enough to degrade the components.
26
27 25. A method of lubricating an engine comprising lubricating the engine
28 with the lubricating oil of Claim 23.
29
30 26. Lubricating oil comprising:
31
32 a major amount of one or more base oils;
33

1 about 1.25 wt. % to about 6 wt. % of one or more dispersants;
2
3 about 2 wt. % to about 6 wt. % of one or more detergents;
4
5 about 0.3 wt. % to about 0.8 wt. % of one or more wear inhibitors; and
6
7 about 0.04 wt. % to about 1.75 wt. % sulfurized isobutylene.
8
9 27. A method of making the lubricating oil of Claim 26 comprising
10 combining about 1.25 wt. % to about 6 wt. % one or more dispersants;
u
12 about 2 wt. % to about 6 wt. % of one or more detergents;
13
14 about 0,3 wt. % to about 0.8 wt. % of one ornnore wear inhibitors; and
15
16 about 0.04 wt. % to about 1.75 wt. % sulfurized isobutylene
17
18 in any order.
19
20 28. A method of lubricating an engine comprising lubricating said engine
21 with the lubricating oil composition of Claim 26.
22
23 29. A method of reducing oxidation in an internal combustion engine which
24 comprises operating an engine with a lubricating oii composition
25 comprising
26
27 a. sulfurized isobutylene and
28
29 b, one or more hindered phenols.
30
31 30. A method of reducing oxidation in an internal combustion engine
32 according to claim 29 wherein said internal combustion engine is a natural
33 gas engine.

1
2 31- The use of an antioxidant system comprising
3
4 a. sulfurized isobutylene and
5
6 b. one or more hindered phenols,
7 to reduce oxidation in an internal combustion engine.
8
9 32. The use of an antioxidant system according to claim 31 wherein the 10 internal combustion engine is a natural gas engine.

33. An antioxidant system, substantially as herein described and exemplified.


Documents:

1436-CHENP-2004 CORRESPONDENCE OTHERS 17-02-2010.pdf

1436-CHENP-2004 OTHER DOCUMENT 09-10-2009.pdf

1436-chenp-2004 abstract-duplicate.pdf

1436-chenp-2004 abstract.pdf

1436-CHENP-2004 AMANDED CLAIMS 09-10-2009.pdf

1436-chenp-2004 claims-duplicate.pdf

1436-chenp-2004 claims.pdf

1436-CHENP-2004 CORRESPONDENCE OTHERS 09-10-2009.pdf

1436-chenp-2004 correspondence-others.pdf

1436-chenp-2004 correspondence-po.pdf

1436-chenp-2004 description (complete)-duplicate.pdf

1436-chenp-2004 description (complete).pdf

1436-chenp-2004 form-1.pdf

1436-chenp-2004 form-13.pdf

1436-chenp-2004 form-18.pdf

1436-chenp-2004 form-26.pdf

1436-CHENP-2004 FORM-3 09-10-2009.pdf

1436-chenp-2004 form-3.pdf

1436-chenp-2004 form-5.pdf

1436-CHENP-2004 OTHER PATENT DOCUMENT 09-10-2009.pdf

1436-chenp-2004 pct.pdf


Patent Number 241145
Indian Patent Application Number 1436/CHENP/2004
PG Journal Number 26/2010
Publication Date 25-Jun-2010
Grant Date 21-Jun-2010
Date of Filing 25-Jun-2004
Name of Patentee CHEVRON ORONITE COMPANY LLC
Applicant Address 6001 BOLLINGER CANYON ROAD, BUILDING T-3RD FLOOR, SAN RAMON, CALIFORNIA 94583
Inventors:
# Inventor's Name Inventor's Address
1 PALAZZOTTO, JOHN, D., 3628 ARCADIAN COURT, CASTRO VALLEY, CA 94546
2 LOGAN, MARK, R., 50 ARENAS COURT, SAN RAMON CA 94583
PCT International Classification Number C10M161/00
PCT International Application Number PCT/US02/38156
PCT International Filing date 2002-11-26
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/997,925 2001-11-29 U.S.A.