The present disclosure relates to methods of improving viscosity shear stability of a lubricating oil and lubricating oil composition comprising: a base oil of lubricating viscosity; an amount of one or more zinc dialkyl dithiophosphate compound(s);
wherein the lubricating oil composition has one or both of the following ratios: a) a ratio of KV40° C..sub.fresh to a weight % of zinc contributed by the one or more zinc dialkyl dithiophosphate compound(s) based on a total weight of the lubricating oil composition, of greater than 510, wherein KV40° C..sub.fresh is the kinematic viscosity of the fresh lubricating oil composition at 40° C.; and b) a ratio of KV40° C..sub.fresh to a weight % of phosphorus contributed by the one or more zinc dialkyl dithiophosphate compound(s) based on a total weight of the lubricating oil composition, of greater than 560, wherein KV40° C..sub.fresh is the kinematic viscosity of the fresh lubricating oil composition at 40° C.

An additive composition for limiting the chemical degradation of hydrocarbonaceous liquids due to nitrogen dioxide contamination at elevated temperature comprises the combination of an ionic liquid composed of a cation and a boron- and halogen-free, multi-functional anion and a detergent additive, the combination of ionic liquid and detergent serving to inhibit the nitration of hydrocarbonaceous liquid components that initiates degradation.

An additive composition for limiting the chemical degradation of hydrocarbonaceous liquids due to nitrogen dioxide contamination at elevated temperature comprises the combination of an ionic liquid composed of a cation and a boron- and halogen-free, multi-functional anion and a detergent additive, the combination of ionic liquid and detergent serving to inhibit the nitration of hydrocarbonaceous liquid components that initiates degradation.

An aspect of the present invention provides a refrigerating machine oil containing a mixed base oil of a first hydrocarbon base oil having a kinematic viscosity at 40° C. of less than 6 mm.sup.2/s and a second hydrocarbon base oil having a kinematic viscosity at 40° C. of 6 mm.sup.2/s or more, wherein a (A)/(B) ratio is more than 1 and 1.5 or less, wherein (A) is a kinematic viscosity at 40° C. of the mixed base oil, and (B) is the kinematic viscosity at 40° C. of the first hydrocarbon base oil.

A lubricating composition for a transmission or gearbox including a mixture of products providing phosphorus to the fluids effective to achieve good adhesive wear and abrasive wear.

A method of limiting the chemical degradation of hydrocarbonaceous liquids due to nitrogen dioxide contamination at elevated temperature comprises the addition thereto of an ionic liquid composed of a cation and a boron- and halogen-free, multi-functional aromatic anion, the ionic liquid serving to inhibit the nitration of hydrocarbonaceous liquid components that initiates degradation.

A method of limiting the chemical degradation of hydrocarbonaceous liquids due to nitrogen dioxide contamination at elevated temperature comprises the addition thereto of an ionic liquid composed of a cation and a boron- and halogen-free, multi-functional aromatic anion, the ionic liquid serving to inhibit the nitration of hydrocarbonaceous liquid components that initiates degradation.

Provided is a lubricating oil composition to be used in an internal combustion engine having a sliding mechanism including a piston ring and a liner, the lubricating oil composition including: a base oil; (A) a poly(meth)acrylate; and (B) an organic molybdenum compound, in which: (A) the poly(meth)acrylate contains a polymer (A1) including a repeating unit derived from a (meth)acrylate represented by the following formula (1) and having a mass-average molecular weight of from 1,000 to 500,000; and a content of (B) the organic molybdenum compound in a total amount of the composition is from 0.01 mass % to 0.2 mass % in terms of a molybdenum atom: wherein R.sup.1 represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a hydrocarbon group having 1 to 60 carbon atoms, or a functional group-containing hydrocarbon group having 1 to 60 carbon atoms.

A lubricating oil composition comprising greater than 50 wt.% of a base oil of lubricating viscosity, and either: a) an additive composition comprising: one or more zinc, dialkyl dithiophosphates (ZDDP compounds) and one or more dispersants, wherein the amount of zinc (Zn) in weight percent provided to the lubricating oil composition by the one or more ZDDP compounds multiplied by the contribution of the total base number (TEN) of the one or more dispersants to the TEN of the lubricating oil composition is a multiplication factor Zn*TBNDisp of at least about 0.06; or b) an additive composition comprising: one or more zinc dialkyl dithiophosphates (ZDDP compounds) and one or more dispersants, wherein the amount of phosphorus (P) in weight percent provided to the lubricating oil composition by the one or more ZDDP compounds multiplied by the contribution of the total base number (TBN) of the one or more dispersants to the TBN of the lubricating oil composition is a multiplication factor P*TBNDisp of at least about 0.051.

A lubricating oil composition comprising greater than 50 wt.% of a base oil of lubricating viscosity, and either: a) an additive composition comprising: one or more zinc, dialkyl dithiophosphates (ZDDP compounds) and one or more dispersants, wherein the amount of zinc (Zn) in weight percent provided to the lubricating oil composition by the one or more ZDDP compounds multiplied by the contribution of the total base number (TEN) of the one or more dispersants to the TEN of the lubricating oil composition is a multiplication factor Zn*TBNDisp of at least about 0.06; or b) an additive composition comprising: one or more zinc dialkyl dithiophosphates (ZDDP compounds) and one or more dispersants, wherein the amount of phosphorus (P) in weight percent provided to the lubricating oil composition by the one or more ZDDP compounds multiplied by the contribution of the total base number (TBN) of the one or more dispersants to the TBN of the lubricating oil composition is a multiplication factor P*TBNDisp of at least about 0.051.