Abstract: To provide a lubricating oil composition for automatic transmission which ensures both a high torque capacity of a wet clutch and a good &mgr;(coefficient of friction)-V (sliding velocity) characteristic in an automatic transmission along with excellent storage stability in a high humidity environment. A lubricating oil composition for automatic transmission is provided, which comprises a lubricating base oil made of a mineral oil and/or a synthetic oil formulated with a friction modifier, a metal detergent and an ashless dispersant, characterized in that said ashless dispersant consists of an succinimide having boron at a rate of three or less atoms in one molecule of the ashless dispersant.

Abstract: This invention is directed to a new low molecular weight copolymer (The PIB/UAR copolymer) that may be prepared by reacting a low molecular weight polyisobutene (PIB) having less than about 32 carbon atoms with an unsaturated acidic reagent in the presence of a free radical initiator. No chain transfer agent is required to prepare the low molecular weight PIB/UAR copolymer. The PIB/UAR copolymer may be useful as is, or as an intermediate for (1) polysuccinimides, (2) detergents or dispersants for lube oil or fuels, (3) pour point depressants and (4) surface sizing agents for paper. The PIB/UAR copolymer may be used by itself or as the ester, amide, imide or metal salt derivative of the PIB/UAR copolymer. The PIB/UAR copolymer may be liquid at ambient temperature.

Abstract: A novel lubricating composition for manual transmissions with improved performance with sintered synchronized components. The lubricating oil composition contains high level of an alkaline earth sulfonate and amine phosphates.

Abstract: The invention relates to a lubricating composition comprising: (a) at least one sulfur-free hydrocarbyl phosphoric acid ester or salt, (b) at least one sulfur-containing hydrocarbyl phosphoric acid or salt, (c) an organic polysulfide, (d) at least one dispersant, and (e) at least one triazole metal deactivator. The composition may also include a thiadiazole derivative. This additive combination provides good antiwear and thermal stability properties, even under severe thermal conditions. These compositions also have good demulsibility properties. The above combination of additives provides the antiwear and extreme-pressure protection necessary for automotive and industrial gear applications. These additives additionally provide this protection without adversely effecting demulsibility properties of the lubricant.

Abstract: An oil composition for heat treatment of a gear which comprises mineral oil having a kinematic viscosity of 5 to 40 mm2/second at 100° C. as a base oil and, based on a total amount of the composition, 0.01 to 5% by weight of (a) a phosphoric acid ester compound and, where necessary, 0.5 to 10% by weight of (b) one compound selected from alkenylsuccinimide compounds, alkylsuccinimide compounds and addition products of boron with alkenylsuccinimide compounds or alkylsuccinimide compounds and 0.5 to 10% by weight of (c) at least one compound selected from salicylates, phenates and sulfonates of alkaline earth metals.

Abstract: This invention relates to a lubricating composition comprising a major amount of an oil of lubricating viscosity with an iodine number less than about 9, (A) one or more antioxidant, and (B) from about 0.01% to about 3% by weight of at least one dispersant or detergent, wherein the total amount of antioxidant is at least about 2% by weight. The additives are useful act controlling oxidation of lubricants. Further, these lubricants have reduced viscosity increase caused by oxidation, while maintaining favorable carbon/varnish ratings.

Abstract: A lubricating oil composition containing a base oil of lubricating viscosity, overbased sulfurized alkylphenate detergent or its calcium salt, an overbased alkylsulfonate detergent or its calcium salt, an ashless dispersant, and a zinc dialkyldithiophosphate and/or zinc diaryidithiophosphate is described. The lubricating oil composition provides improved heat stability and anti-wear performance in marine diesel engines operated under severe conditions where the cylinder liner temperature may reach 200 to 260° C.

Abstract: A low phosphorous lubricating oil composition for internal combustion engines comprising an alkylthiocarbamate compound of the formula: wherein each of R1, R2, R3, and R4 independently represents an alkyl group of 1-18 carbon atoms, and (X) represents S, S—S, S—CH2—S, S—CH2CH2—S, S—CH2CH2CH2—S, or S—CH2CH(CH3)—S, and additive compositions and additive packages utilizing the above compound.

Abstract: Disclosed is an additive composition that can be mixed with various types of basic oils to produce a lubricant that can meet the international standards of manual truck gearbox oils. A preferred embodiment includes various quantities of an isobutylene sulfide, zinc dialklydithiophosate and other components. Component properties of the additive composition are selected to produce a lubricant that has good thermal stability, rust-resisting and endurance qualities and that has a low cost of use and production.

Abstract: The invention concerns a lubricant for a two-stroke slow speed crosshead marine engine, powered with a fuel with sulfur content not less than 1%, consisting of a mixture of distillates used as lubricating bases containing x wt. % of dispersing additive of the succinimide type, y wt. % of an overbased detergent additive of the sulfonate type, and z wt. % of an overbased detergent additive of the phenate type. The invention is characterized in that x, y and z are selected in the intervals 0.5≦x≦2.5, 2.5≦y≦10 and 11≦z≦24.5 such that 15≦x+y+z≦36 and 1.5≦y/x≦13, the BN of the lubricant, determined according to the ASTM D-2896 standard, is not less than 70 mg KOH/g, and the speed at which sulfuric acid is neutralized by the lubricant, defined by the maximum speed of pressure increase of a closed chamber, with its walls covered with a film of said lubricant from 80 to 100 &mgr;m thick, maintained at 100° C.

Abstract: To provide a lubricating oil composition for continuously variable transmission which ensures both a high coefficient of friction between metals required for a push belt-type CTV oil and excellent oxidation stability guaranteeing the performance over a long time.

Abstract: To provide a lubricating oil composition for automatic transmission which ensures both a high torque capacity of a wet clutch and a good &mgr;(coefficient of friction)-V (sliding velocity) characteristic in an automatic transmission along with excellent storage stability in a high humidity environment.

Abstract: This invention relates to a lubricating composition comprising a blend of a major amount of an oil of lubricating viscosity, gear or transmission oil package and a top treatment which comprises at least one saturated fatty phosphate ester or salt, wherein the lubricating composition is free of saturated fatty phosphites. Tin another embodiment, the invention relates to a lubricating composition comprising a major amount of an oil of lubricating viscosity, at least one saturated fatty phosphate ester or salt, at least one polysulfide and at least one phosphorus antiwear or extreme pressure agent, wherein the lubricating composition is free of saturated fatty phosphites. The invention relates to additive combinations which when added to a lubricant can provide and improve frictional and, optionally, thermal stability properties. The additives include a phosphate ester or salt wherein the hydrocarbyl group of the phosphate is a fatty-saturated group.

Abstract: There is disclosed a lubricating oil composition for cellulose base wet friction material which comprises a base oil blended with (A) a boron-containing imide base dispersant (e.g. boron treated polyalkenyl succinimide) having a weight-average molecular weight in the range of 500 to 3000 and having a ratio by weight of boron to nitrogen (B/N) in the range of 0.1 to 1.5 in such a blending amount that the boron content and the nitrogen content each derived from the component (A) are made to be at least 60 ppm by weight and at least 100 ppm by weight, respectively based on the base oil. The above lubricating oil composition enhances peeling resistant durability for a friction material, especially a cellulose base friction material without impairing the wear resistance or scoring resistance of a steel material element, and is well suited for use in a cellulose base friction material for a starting and running device and a transmission clutch that are used in an automatic transmission of an automobile.

Abstract: Automatic transmission fluids are described which contain at least 0.2 wt % of a metal-containing detergent, a dispersant, and a mixture of friction modifiers. The transmission fluids according to the present invention exhibit excellent initial anti shudder properties, excellent anti-shudder durability, and excellent friction durability.

Abstract: Continuously variable transmission can be lubricated by supplying to them a composition of (a) an oil of lubricating viscosity; (b) a dispersant; and (c) a detergent. At least one of the dispersant (b) and the detergent (c) is a borated species, and the amount of boron present in the composition is sufficient to impart improved friction and anti-seizure properties to the composition when employed in said transmission.

Abstract: A lubricating oil composition containing a base oil of lubricating viscosity, overbased sulfurized alkylphenate detergent or its calcium salt, an overbased alkylsulfonate detergent or its calcium salt, an ashless dispersant, and a zinc dialkyldithiophosphate and/or zinc diaryidithiophosphate is described. The lubricating oil composition provides improved heat stability and anti-wear performance in marine diesel engines operated under severe conditions where the cylinder liner temperature may reach 200 to 260° C.

Abstract: A gas-fuelled engine lubricating oil composition having a TBN in the range of 2 to 20 and comprising:

Abstract: A heavy duty diesel engine lubricating oil composition having no more than 0.10 wt. % phosphorus comprises an ashless dispersant, a neutral calcium phenate, an overbased calcium or magnesium sulfonate, a metal dihydrocarbyldithiophosphate, and a phenolic or aminic antioxidant.

Abstract: This invention relates to a lubricating composition comprising a blend of a major amount of an oil of lubricating viscosity, gear or transmission oil package and a top treatment which comprises at least one saturated fatty phosphate ester or salt, wherein the lubricating composition is free of saturated fatty phosphites. Tin another embodiment, the invention relates to a lubricating composition comprising a major amount of an oil of lubricating viscosity, at least one saturated fatty phosphate ester or salt, at least one polysulfide and at least one phosphorus antiwear or extreme pressure agent, wherein the lubricating composition is free of saturated fatty phosphites. The invention relates to additive combinations which when added to a lubricant can provide and improve frictional and, optionally, thermal stability properties. The additives include a phosphate ester or salt wherein the hydrocarbyl group of the phosphate is a fatty-saturated group.

Abstract: Lubricant compositions comprises a lubricant base oil and one or more compounds resulting the modification of a succinimide represented by formula (1) or (2) 1

Abstract: A low viscosity lubricating oil composition having a CCS viscosity less than 3500 mPa.s at −25° C. and having no more than 0.16 mass % of phosphorus which comprises a dispersant, and a detergent of calcium or magnesium or both; and optionally a zinc dihydrocarbyldithiophosphate, a viscosity modifier, a pour point depressant and an antioxidant. The oil satisfies the Cummins M11 cross-head wear engine test specification in a low phosphorus and low viscosity formulation.

Abstract: A succinimide composition is prepared by reacting a mixture of an alkenyl or alkylsuccinic acid derivative, an unsaturated acidic reagent copolymer, and a polyamine under reactive conditions; then treating the reaction product with either a cyclic carbonate or a linear mono- or polycarbonate or boron compound under reactive conditions. The alkenyl or alkyl substituent of the alkenyl or alkylsuccinic acid derivative has a Mn of from 1800 to 3000. The unsaturated acidic reagent copolymer has a Mn of from 2000 to 4800, and is a copolymer of an unsaturated acidic reagent and an olefin having an average of from 14 to 30 carbon atoms. The polyamine has at least three nitrogen atoms and 4 to 20 carbon atoms. The mixture contains from 1.5 to 10 equivalents of the alkenyl or alkylsuccinic acid derivative per equivalent of unsaturated acidic reagent copolymer and from 0.4 to 1.0 moles of polyamine per equivalent of alkenyl or alkylsuccinic acid derivative plus unsaturated acidic reagent copolymer.

Abstract: A hydraulic oil, a predominant amount of an oil having a viscosity suitable for lubrication, and from 0.03% to 0.06% of an agent improving filterability, corresponding to the formula R—Z. Z represents an ester of succinic acid comprising the reaction product of a succinic anhydride and an aliphatic polyhydric alcohol; or a succinimide comprising the reaction product of a succinic anhydride and a polyamine, the said reaction product being treated with an after-treatment agent. R represents a polyolefin having a molecular weight (Mn) of 500 to 2500 and an Mw/Mn ratio of 1 to 5.

Abstract: The lubricating oil of the present invention exhibits an excellent effect of agglomerating solid impurity particles it contains to a sufficiently large size as to be captured and removed by an oil filter.

Abstract: The present invention provides for a lubricant oil composition for internal combustion engines, that resists oxidation in the presence of NOx and evaporation characteristics, and controls poisoning of a three-way catalyst system for occluding/reducing NOx and formation of deposit in an air intake system. The lubricant oil composition for internal combustion engines, comprises a base oil, which contains aromatic compounds at 1 wt. % or less, sulfur at 10 ppm or less, and paraffin and monocyclic naphthene compounds at 50 wt. % or more as total content, and has a kinematic viscosity of 2 to 50 mm2/s at 100° C. and evaporated quantity of 16 wt. % or less determined by the NOACK evaporation test, wherein the base oil is incorporated with a zinc dithiophosphate at 0.04 to 0.10 wt. % as phosphorus, a calcium phenate and/or calcium sulfonate having a total basic number of 100 to 400 mg KOH/g at 1 to 10 wt. %, and a polyalkenyl succinimide having a boron/nitrogen wt. ratio of 0 to 1.

Abstract: A heavy duty diesel engine lubricating oil composition having no more than 0.10 wt. % phosphorus comprises an ashless dispersant, a neutral calcium phenate, an overbased calcium or magnesium sulfonate, a metal dihydrocarbyldithiophosphate, and a phenolic or aminic antioxidant.

Abstract: Concentrates for lubricating oil compositions are prepared by mixing at elevated temperature: (i) at least one high molecular weight ashless dispersant; (ii) at least one oil-soluble overbased metal detergent; and (iii) at least one surface-active agent comprising a low molecular weight hydroxyl or amine group.

Abstract: Lubricant compositions comprises a lubricant base oil blended with a boron-containing ashless dispersant (A) in an amount of 0.035 or more percent of boron by mass, and an alkaline earth metal sulfonate having a total base number of 50 to 500 mgKOH/g (B) in an amount of 0.01 or more percent of alkaline earth metal by mass, all the percentages being based on the total mass of the composition and if necessary a phosphorus additive. The lubricant compositions are superior in effect to enhance the dynamic- and static-friction coefficients in a wet clutch.

Abstract: There is disclosed a traction drive fluid which comprises a base oil blended with (A) an active phosphate ester base compound, (B) a boron-containing imide base dispersant (e.g. polyalkenyl succinimide treated with a boron compound) and (C) a boron-free imide base dispersant (e.g. polyalkenyl succinimide) in such blending amounts that the phosphorus content derived from the component (A) and the boron content derived from the component (B) are each 100 to 600 ppm, preferably 60 to 300 ppm by weight, and at least 60 ppm by weight, respectively based on the base oil, and the boron-free imide base dispersant (C) is blended so that the ratio by weight of the nitrogen in the component(C) to the boron in the component (B) is at least 1, preferably 1 to 6.

Abstract: A lubricating oil composition containing a base oil of lubricating viscosity, overbased sulfurized alkylphenate detergent or its calcium salt, an overbased alkylsulfonate detergent or its calcium salt, an ashless dispersant, and a zinc dialkyldithiophosphate and/or zinc diaryldithiophosphate is described. The lubricating oil composition provides improved heat stability and anti-wear performance in marine diesel engines operated under severe conditions where the cylinder liner temperature reach 200 to 260° C.

Abstract: The invention provides dispersants and dispersant viscosity index improvers which include polymers of conjugated dienes which have been hydrogenated, functionalized, optionally modified, and post treated. The dispersant substances include a copolymer of two different conjugated dienes and an aryl-substituted olefin. The polymers are selectively hydrogenated to produce polymers which have highly controlled amounts of unsaturation, permitting highly selective functionalization. Also provided are lubricant fluids, such as mineral and synthetic oils, which have been modified in their dispersancy and/or viscometric properties by means of the dispersant substances of the invention. Also provided are methods of modifying the dispersancy and/or viscometric properties of lubricating fluids such as mineral and synthetic lubricating oils. The dispersant substances may also include a carrier fluid to provide dispersant concentrates.

Abstract: There is disclosed a lubricating oil composition for automatic transmissions which comprises a base oil comprising at least one oil selected from the group consisting of a mineral oil and a synthetic oil each having a specific kinematic viscosity and a % CA; (A) a non-boron based succinic acid imide (e.g. polybutenylsuccinic acid imide) and a boron based succinic acid imide each in an amount of 0.1 to 5% by weight based on the whole composition; (B) a condensation product of a branched chain fatty acid having 8 to 30 carbon atoms (e.g. isostearic acid) and an amine (e.g. tetraethylene-pentamine) in an amount of 0.05 to 2% by weight based on the same; and (C) a dialkyl hydrogenphosphite (e.g. dioleyl hydrogenphosphite) in an amount of 0.1 to 1% by weight based on the same, and optionally at least one member selected from viscosity index improvers, antioxidants, metal deactivators, defoaming agents, detergents, extreme pressure agents and rust preventives.

Abstract: The present invention provides a lubricant oil composition for an automatic and continuously variable transmission with a built-in torque converter equipped with a lock-up clutch, which is incorporated, in the base oil, with a compound containing at least one type of cyclic carboxylic acid imide having boron in the molecule and substituted by an alkyl or alkenyl group, wherein the cyclic carboxylic acid imide is contained at 0.1 to 12 wt % based on the whole composition.

Abstract: The invention provides dispersants and dispersant viscosity index improvers which include polymers of conjugated dienes which have been hydrogenated, functionalized, optionally modified and post treated. The dispersant substances include a copolymer of two different conjugated dienes. The polymers are selectively hydrogenated to produce polymers which have highly controlled amounts of unsaturation, permitting highly selective functionalization. The polymers may be functionalized by grafting of heteroatom-containing olefins. Also provided are lubricant fluids, such as mineral and synthetic oils, which have been modified in their dispersancy and/or viscometric properties by means of the dispersant substances of the invention. Also provided are methods of modifying the dispersancy and/or viscometric properties of lubricating fluids such as mineral and synthetic lubricating oils. The dispersant substances may also include a carrier fluid to provide dispersant concentrates.

Abstract: A lubricating oil composition is provided, which comprises a lubricating base oil and based on the whole weight of the lubricating oil composition, (A) 0.5 wt % to 10 wt % of a metal salicylate having a total base number of from 100 mg-KOH/g to 195 mg-KOH/g, (B) 0.1 wt % to 10 wt % of a diarylamine compound, (C) 0.1 wt % to 10 wt % of a hindered phenol compound, and (D) 1 wt % to 10 wt % of a polyalkenylsuccinimide and/or a boron-containing polyalkenylsuccinimide. Also provided is a lubricating oil composition which further comprises 0.1 wt % to 10 wt % of a metal phenate having a total base number of from 100 mg-KOH/g to 300 mg-KOH/g as a component (E) in addition to the above components (A) to (D). The lubricating oil composition is excellent in all properties of detergency, NO.sub.x oxidation resistance and thermal oxidation resistance and suitable as a long-life engine oil for gas engine heat pumps.

Abstract: Concentrates for lubricating oil compositions are prepared by mixing at elevated temperature:(i) at least one high molecular weight ashless dispersant;(ii) at least one oil-soluble overbased metal detergent; and (iii) at least one other concentrate additive provided that the additive is first mixed with the detergent or the dispersant.

Abstract: Hydrocarbyl substituted C.sub.4 to C.sub.10 monounsaturated dicarboxylic acid, anhydrides or esters, e.g. polyisobutenyl succinic anhydride, preferably made by reacting polymer of C.sub.2 to C.sub.10 monoolefin, preferably polyisobutylene, having a molecular weight of about 1500 to 5,000, preferably with a C.sub.4 to C.sub.10 monounsaturated acid, anhydride or ester, preferably maleic anhydride, such that there are 1.05 to 1.25 dicarboxylic acid producing moieties per molecule of said olefin polymer used in the reaction mixture. The resulting materials are useful per se as oil additives, or may be further reacted with amines, alcohols, amino alcohols, boric acid, etc. to form dispersants.

Abstract: The invention provides synergistic combinations of phosphorus acid-containing compounds with ashless antioxidants. These combinations dramatically improve the oxidation stability of lubricating compositions, particularly power transmission fluids such as automatic transmission fluids.

Abstract: A succinimide composition is prepared by reacting a mixture of a polyalkenyl derivative, an unsaturated acidic reagent copolymer, and a polyamine under reactive conditions. The polyalkenyl derivative is produced by reacting an unsaturated acidic reagent with a polyalkene in the presence of a strong acid. The unsaturated acidic reagent copolymer is a copolymer of an unsaturated acidic reagent and an olefin.

Abstract: A polysuccinimide composition is prepared by reacting a mixture of an alkenyl or alkylsuccinic acid derivative, an unsaturated acidic reagent copolymer, and a polyamine under reactive conditions. The alkenyl or alkyl substituent of the alkenyl or alkylsuccinic acid derivative has a Mn of from 140 to 3000. The unsaturated acidic reagent copolymer has an average degree of polymerization of from 2 to 20, and is a copolymer of an unsaturated acidic reagent and an olefin having a Mn of at least 1000. The polyamine has at least three nitrogen atoms and has from 4 to 20 carbon atoms.

Abstract: The present invention provides an ashless lubricating oil composition that improves the corrosion properties in natural gas engines. The ashless lubricating oil composition comprises:a) a major amount of base oil of lubricating viscosity;b) from about 1 to 6 wt % of an untreated polyalkylene or polyalkenyl succinimide dispersant; andc) from about 1 to 6 wt % of a borated polyalkylene or polyalkenyl succinimide dispersant.

Abstract: A lubricating oil composition for internal combustion engines which comprises a base oil, (a) an ashless dispersant containing boron, (b) a metallic detergent, and optionally (c) at least one selected from a group consisting of esters of aromatic carboxylic acids having hydroxyl group and hydroxy compounds and compounds containing boron which are derived from the esters, wherein a ratio [B]/[M] of a content of boron [B] in the composition in % by weight to a total content of metals [M] derived from the detergent in the composition in % by weight is not less than 0.15, and a sulfated ash content in the composition is not more than 1.5% by weight. The lubricating oil composition has a low ash content, does not show adverse effects on the performance of apparatuses for exhaust gas treatment, and exhibits excellent resistance to coking and oxidation stability.

Abstract: Gear oils and gear oil additive concentrates of enhanced positraction performance are described. They comprise: (i) at least one oil-soluble sulfur-containing extreme pressure or antiwear agent; (ii) at least one oil-soluble amine salt of a partial ester of an acid of phosphorus; and (iii) at least one oil-soluble succinimide of the formula ##STR1## where R.sub.1 is an alkyl or alkenyl group having an average of 8 to 50 carbon atoms, and each of R.sub.2, R.sub.3 and R.sub.4 is a hydrogen atom or an alkyl or alkenyl group having an average of up to about 4 carbon atoms. These compositions preferably contain one, more preferably two, and most preferably all three of the following additional components: (iv) at least one amine salt of a carboxylic acid; (v) at least one nitrogen-containing ashless dispersant; and (vi) at least one trihydrocarbyl ester of a pentavalent acid of phosphorus.

Abstract: This invention provides a composition and method for producing partial synthetic automatic transmission fluids having improved shear-stability and low temperature properties without the need to incorporate polymeric viscosity modifiers.

Abstract: A lubricating oil composition for internal combustion engines giving improved soot dispersancy. That lubricating oil composition has a mixture of borated and carbonated polyalkylene succinimides derived from different molecular weight polyalkylenes. The molecular weight of the polyalkylenes from which the carbonated polyalkylene succinimide is derived is at least 300 greater than the molecular weight of the polyalkylenes from which the borated polyalkylene succinimide is derived.

Abstract: Oil-based functional fluid compositions formulated for use as automatic transmission fluid, fluid for a wet brake system, or a friction-depending lubricant are improved by including in the composition a minor amount of at least one alcohol or polyol having less than 12 carbon atoms in the molecule. This results in a desirable increase in the dynamic and/or static coefficients of friction of automatic transmission or other frictional surfaces contacted by the composition. Preferred for this use is a composition formed by heating at least one ashless dispersant containing basic nitrogen and/or at least one hydroxyl group with a combination of at least (i) an inorganic acid of phosphorus, (ii) a boron compound, and (iii) a polyol having less than 12 carbon atoms, so that a liquid composition is formed. The boron compound and the inorganic phosphorus acid are preferably co-present during the heating.

Abstract: A terpolymer having an average M.sub.n of from 600 to 100,000 is obtained by the terpolymerization of a 1-olefin having from 10 to 30 carbon atoms, maleic anhydride, and a 1,1 -disubstituted polyisobutylene having an average M.sub.n of from 500 to 5,000.

Abstract: Hydrocarbyl substituted C.sub.4 to C.sub.10 monounsaturated dicarboxylic acid, anhydrides or esters, e.g. polyisobutenyl succinic anhydride, preferably made by reacting polymer of C.sub.2 to C.sub.10 monoolefin, preferably polyisobutylene, having a number arrange molecular weight of about 700 to 1200, preferably with a C.sub.4 to C.sub.10 monounsaturated acid, anhydride or ester, preferably maleic anhydride, such that there are 1.2 to 2.0 dicarboxylic acid producing moieties per molecule of said olefin polymer used in the reaction mixture. The resulting materials may be further reacted with amines, alcohols, amino alcohols, boric acid, etc. to form dispersants.

Abstract: A lubricating oil composition for a high-speed gear particularly having a peripheral speed of 10 m/sec or more is herein disclosed which is obtained by blending a base oil having a % C.sub.A of 5 or less and preferably further having a nitrogen content of 50 ppm or less and a sulfur content of 50 ppm or less with a sulfur additive, a phosphorus additive and a nitrogen additive so that an element ratio 100N/(S+P) in the composition may be in the range of 4 to 10 by weight, and the lubricating oil composition has a sufficient hypoid gear performance, can inhibit the formation of a sludge, and permits the prolongation of the life of an oil seal for use in a high-speed and/or a high-temperature rotating portion.