Provided is a grease composition containing a base oil, a thickener, and an additive. The base oil contains a poly--olefin and has a kinematic viscosity of 20-60 mm.sup.2/s at 40 C. The thickener contains a urea compound produced by reacting a diisocyanate compound with a mixed amine containing an alicyclic amine and an aromatic amine. The additive contains a phosphorous acid ester, an ether compound, and an oxidized paraffin.

Provided is a refrigerating machine oil composition for a mixed refrigerant comprising difluoromethane, the composition comprising a polymer (A) below and an ester (B) of polyhydric alcohol(s) with aliphatic monocarboxylic acid(s).

The polymer (A): a polymer which is obtained by polymerizing monomer(s) consisting of at least one monomer of monosubstituted ethylenes and disubstituted ethylenes, and in which a ratio of a monomer represented by the following general formula (I):

##STR00001##

wherein R.sup.1 represents an alkyl group having 1 to 14 carbon atoms, R.sup.2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and the sum of carbon numbers in R.sup.1 and R.sup.2 is 2 to 14, is 75 to 100% by mass based on a total mass of monomers constituting the polymer.

A polyester is useful as a high viscosity base fluid. A method for its preparation involves epoxidizing an alpha-olefin, reacting the alpha-epoxide or diol with a saturated linear aliphatic dicarboxylic acid, and isolating the polyester. Lubricant compositions can contain such polyesters and the compositions are useful as automatic transmission fluids, manual transmission fluids, continuously variable transmission fluids, gear oil formulations, industrial gear oil formulations, axle fluid formulations, dual clutch transmission fluids, dedicated hybrid transmission fluids, or as hydraulic oils.

A method for improving wear control in an engine or other mechanical component lubricated with a lubricating oil 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 encapsulated boron-containing microscale particles, as a minor component. The minor component preferably contains no metal or sulfur, and preferably no phosphorus. The encapsulated boron-containing microscale particles include an encapsulating material and a boron-containing compound encapsulated by the encapsulating material. The boron-containing compound is a boron oxide, a boric acid, or mixtures thereof. The encapsulating material is a carboxylic acid selected from an aliphatic carboxylic acid, a cycloaliphatic carboxylic acid, an aromatic carboxylic acid, and mixtures thereof. The lubricating oils are useful in internal combustion engines.

A fluid contains a base oil consisting of an alcohol-initiated polyalkylene glycol where polyalkylene glycol component is selected from a homopolymer of 1,2-butylene oxide and copolymer of 1,2-butylene oxide and propylene oxide; a glycerol-initiated unsaturated ester that is free of tertiary carbon atoms and quaternary carbon atoms; and an antioxidant.

The present invention provides a viscosity index improver having an excellent viscosity index improving effect, a lubricant composition having excellent low-temperature viscosity in which the viscosity reduction due to long-term use is small, and a method for producing the lubricant composition. A viscosity index improver of the present invention contains a copolymer (A) containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number (Q) of 29 or more, and the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer (A).

A lubricant, which includes an ionic liquid including a conjugate base and a conjugate acid, wherein the conjugate acid has a group including a straight-chain hydrocarbon group having 6 or more carbon atoms, a pKa of an acid that is a source of the conjugate base in acetonitrile is 10 or less, and solubility of the ionic liquid to CF.sub.3(CHF).sub.2CF.sub.2CF.sub.3 is 0.1 parts by mass relative to 100 parts by mass of CF.sub.3(CHF).sub.2CF.sub.2CF.sub.3.

The present invention provides a working fluid composition for a refrigerating machine, comprising a refrigerating machine oil that comprises an ester of a polyhydric alcohol and a fatty acid, an epoxy compound, and a phosphorus compound, and a fluoropropene refrigerant, wherein the polyhydric alcohol constituting the ester comprises pentaerythritol and dipentaerythritol, the fatty acid constituting the ester comprises at least one selected from fatty acids having 4 to 9 carbon atoms, and the epoxy compound and the phosphorus compound satisfy a condition represented by the following formula (1). $\begin{array}{cc}\left[\mathrm{Formula}1\right]& \\ 0.10\frac{\left(\frac{N_E}{M_E}.Math.W_E\right)}{\left(\frac{N_P}{M_P}.Math.W_P\right)}1.50& \left(1\right)\end{array}$

An aqueous based metalworking fluid that is environmentally friendly and process for metalworking with the fluid. The metalworking fluid is sampled at periodic intervals and replenished to predetermined operating specifications with the aqueous based metalworking fluid without the need for individual boosters.

The invention provides a grease composition for rolling bearings that can exhibit improved bearing life that can secure the low noise performance under high temperature conditions, and a rolling bearing where the above-mentioned grease composition is enclosed. The grease composition for rolling bearings includes a base oil, a urea thickener and a metal deactivator. The base oil has an aniline point of 110 C. or more. The urea thickener is at least one kind of diurea compound selected from the group consisting of diurea compounds represented by formula (1): R.sup.1NHCONHR.sup.2NHCONHR.sup.3 (wherein R.sup.1 and R.sup.3, which may be the same or different from each other represent a C.sub.6-30alkyl group, a C.sub.5-8cycloalkyl group or a C.sub.6-10aryl group, and R.sup.2 represents a bivalent aromatic hydrocarbon group having 6 to 15 carbon atoms.)