Abstract: The disclosed technology relates to a lubricating oil composition comprising at least one base oil and at least one overbased low molecular weight zinc dialkyldithiophosphate derived from one or more dithiophosphoric acids represented by the formula (I) and/or a metal salt thereof, wherein in formula (I), R1 and R2 are independently hydrocarbyl groups, the average total number of carbon atoms in R1 and R2 in formula (I) being in the range from 4 to 10, the metal ratio of the overbased low molecular weight zinc dialkyldithiophosphate being at least about 1.15:1, the lubricating oil composition being characterized by a phosphorus concentration of up to about 0.12% by weight. The disclosed technology also relates to a method of lubricating an internal combustion engine and improving the efficiency of the emissions control system of the engine.

Abstract: An internal combustion engine with a catalyst-containing exhaust-gas aftertreatment device is lubricated with a composition of a base oil; and a zinc salt of a mixture of phosphorus-containing compounds having hydrocarbyl groups R1 and R2 where the average total number of carbon atoms in R1 plus R2 for the mixture of phosphorus-containing compounds is at least 9.5, where 4 to 30 weight percent of such groups contain 2 to 4 carbon atoms and where in less than 8 mole percent of the phosphorus-containing molecules in the mixture of phosphorus-containing compounds each of R1 and R2 contain 2 to 4 carbon atoms.

Abstract: Internal combustion engines exhibit improved efficiency of the emissions control system by using a lubricating oil composition of a base oil, an alkali or alkaline earth metal-containing detergent; a metal salt of one or more phosphorus-containing compounds represented by the formula (I), wherein X1 and X2 are independently O or S, and R1 and R2 are independently hydrocarbyl groups, the average total number of carbon atoms in R1 and R2 for the one or more phosphorus-containing compounds being at least 10.4; and an acylated nitrogen-containing compound having at least about 10 alphatic carbon atoms and a TBN of at least about 2; the lubricating oil composition being characterized by a phosphorus concentration of up to about 0.12% by weight and the substantial absence of copper, thereby generating a lean-phosphorus containing exhaust gas.

Abstract: A composition for lubricating an internal combustion engine includes an oil of lubricating viscosity; a predominantly linear alkylbenzenesulfonate detergent having a metal ratio of at least 8; and a combination of hindered phenolic ester antioxidant and aromatic amine antioxidant. The amount of any phenate detergent is less than 15% by weight of the total amount of detergents.

Abstract: An internal combustion engine with a catalyst-containing exhaust-gas aftertreatment device is lubricated with a composition of a base oil; and a zinc salt of a mixture of phosphorus-containing compounds having hydrocarbyl groups R1 and R2 where the average total number of carbon atoms in R1 plus R2 for the mixture of phosphorus-containing compounds is at least 9.5, where 4 to 30 weight percent of such groups contain 2 to 4 carbon atoms and where in less than 8 mole percent of the phosphorus-containing molecules in the mixture of phosphorus-containing compounds each of R1 and R2 contain 2 to 4 carbon atoms.

Abstract: Internal combustion engines exhibit improved efficiency of the emissions control system by using a lubricating oil composition of a base oil, an alkali or alkaline earth metal-containing detergent; a metal salt of one or more phosphorus-containing compounds represented by the formula (I), wherein X1 and X2 are independently O or S, and R1 and R2 are independently hydrocarbyl groups, the average total number of carbon atoms in R1 and R2 for the one or more phosphorus-containing compounds being at least 10.4; and an acylated nitrogen-containing compound having at least about 10 alphatic carbon atoms and a TBN of at least about 2; the lubricating oil composition being characterized by a phosphorus concentration of up to about 0.12% by weight and the substantial absence of copper, thereby generating a lean-phosphorus containing exhaust gas.

Abstract: A composition for lubricating an internal combustion engine includes an oil of lubricating viscosity; a predominantly linear alkylbenzenesulfonate detergent having a metal ratio of at least 8; and a combination of hindered phenolic ester antioxidant and aromatic amine antioxidant. The amount of any phenate detergent is less than 15% by weight of the total amount of detergents.

Abstract: A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and an additive system comprising (A) from about 0.1 to about 5% by weight of a detergent composition comprising at least two metal overbased compositions wherein said detergent composition consists essentially of (A-1) at least one alkali metal overbased detergent and (A-2) at least one calcium overbased detergent, wherein the ratio of total base number on a per 100 TBN and diluent-free basis contributed by the alkali metal detergent to the total base number contributed by the calcium detergent ranges from about 99.5-20 to about 0.5-80; (B) from about 1 to about 10% by weight of a succinimide dispersant; and (C) from about 0.1 to about 5 % by weight of a metal dihydrocarbyl dithiophosphate of the formula (I) wherein R1 and R2 are each, independently, hydrocarbyl groups containing from 3 to 13 carbon atoms, M is a metal and n is an integer equal to the valence of M.

Abstract: A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and an additive system comprising (A) from about 0.1 to about 5 % by weight of a detergent composition comprising at least two metal overbased compositions wherein said detergent composition consists essentially of (A-1) at least one alkali metal overbased detergent and (A-2) at least one calcium overbased detergent, wherein the ratio of total base number on a per 100 TBN and diluent-free basis contributed by the alkali metal detergent to the total base number contributed by the calcium detergent ranges from about 99.5-20 to about 0.5-80; (B) from about 1 to about 10 % by weight of a succinimide dispersant; and (C) from about 0.1 to about 5 % by weight of a metal dihydrocarbyl dithiophosphate of the formula (I) wherein R1 and R2 are each, independently, hydrocarbyl groups containing from 3 to 13 carbon atoms, M is a metal and n is an integer equal to the valence of M.