The present disclosure relates to lubricant additives such as dispersants and dispersant viscosity modifiers including acyl peptide grafted polymers and lubricating oil compositions comprising such additives. The disclosure also relates to the use of lubricant compositions comprising the additives herein for improving the soot or sludge handling characteristics of an engine lubricant composition and while minimizing the deterioration of engine's elastomer compatibility.

The present invention provides a lubricant composition comprising a base oil of lubricating viscosity, wherein the base oil comprises an ether base stock of formula (A), where: R.sub.a and R.sub.b are aliphatic hydrocarbyl groups and may be the same or different; the lubricant composition further comprising at least one aminic anti-oxidant and at least one phenolic anti-oxidant. In some embodiments, the ether base stock has the formula (1), where: R.sub.1 R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are as defined herein. The lubricant composition may be used for lubricating a surface in an internal combustion engine as well as for improving the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

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The present invention provides a lubricant composition for an internal combustion engine comprising a base oil of lubricating viscosity, wherein the base oil comprises an ether base stock of formula (A): where: R.sub.a and R.sub.b are aliphatic hydrocarbyl groups and may be the same or different; wherein at least one of R.sub.a and R.sub.b is branched-chain alkyl, alkoxy-substituted-alkyl or cycloalkyl-substituted-alkyl; the lubricant composition further comprising: i) at least one molybdenum compound as a lubricant additive which is present, on a molybdenum element basis, in an amount of at least 0.06% by weight of the lubricant composition; or ii) at least one polymethacrylate compound as a lubricant additive which is present in an amount of from 0.1 to 7.5% by weight of the lubricant composition. The lubricant composition may be used for lubricating a surface in an internal combustion engine as well as for improving the fuel economy performance and/or piston cleanliness performance and/or turbocharger cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

A method for improving oxidative stability of a lubricating oil in a diesel engine by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one aminic antioxidant, at least one phenolic antioxidant, and at least one Group V base stock as minor components. The at least one aminic antioxidant is present in an amount from 0.1 to 2.5 wt. %, the at least one phenolic antioxidant is present in an amount from 0.5 to 5 wt. %, and the at least one Group V base stock is present in amount from 1 to 20 wt. %. Oxidative stability is improved in a diesel engine lubricated with the lubricating oil, as compared to oxidative stability achieved in a diesel engine lubricated with a lubricating oil containing a minor component other than specified antioxidants and Group V base stock.

The invention provides a lubricating oil for fluid dynamic bearing including as a base oil a monoester oil free of unsaturated bond, and having an absolute viscosity of 2.0 to 3.0 mPa.Math.s at 100 C. a viscosity index of 130 or more and a pour point of 20 C. or less.

The disclosed technology relates to a lubricating composition additives that prevent or reduce seals degradation, especially in the presence of basic amine compounds which impart basicity (measured as total base number or TBN) to the lubricating composition. The lubricating composition contains (a) an oil of lubricating viscosity, (b) a basic amine compound, and (c) a 1,3-dioxane-4,6-dione compound.

A novel hydraulic (e.g., a biohydraulic) fluid which has high performance attributes is disclosed herein. Such a novel hydraulic fluid includes a contribution of a range of 10% up to about 85% by weight of at least one of: natural esters, synthetic esters, polyols, a vegetable oil, 1% up to about 40% by weight of polyalphaolefin (PAO), 1% up to about 40% by weight of polyalkylene glycol (PAG), and mixtures thereof, and wherein up to about 10% by weight quantity of one or more additives are introduced to provide desired properties that include at least one of: a high viscosity index, a low pour point, a hydrolytic stability, and an oxidative stability, as part of the hydraulic fluid contribution.

Provided is a lubricating oil composition containing a refined paraffinic mineral oil (A) and an alkylbenzene (B) having a flash point of 160 C. or higher, and having a flash point of 250 C. or higher. The lubricating oil composition has a high flash point of 250 C. or higher and has an excellent long lifetime to such an extent that the lubricating oil composition can maintain excellent oxidation stability even in long-term use in high-temperature environments.

The present invention provides a refrigerating machine oil comprising: a base oil comprising an ester of a polyhydric alcohol and a fatty acid comprising 20 to 100% by mol of a branched fatty acid having 4 to 9 carbon atoms; and 0.2 to 0.5% by mass of a phenol-based antioxidant based on a total amount of the refrigerating machine oil, and the refrigerating machine oil being used with trifluoroethylene refrigerant.

The disclosed technology relates to a lubricating composition additives that prevent or reduce seals degradation, especially in the presence of basic amine compounds which impart basicity (measured as total base number or TBN) to the lubricating composition. The lubricating composition contains (a) an oil of lubricating viscosity, (b) a basic amine compound, and (c) a 1,3-dioxane-4,6-dione compound.