A refrigerator oil composition with a base oil (A), and a first phosphorus compound (B). The first phosphorus compound (B) is a first phosphite ester (B1) represented by formula (1) and a second phosphite ester (B2) represented by formula (2):

(R.sup.11—O—).sub.n—PO—R.sup.12).sub.3-n   (1)

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A method of producing a refrigerator oil composition by mixing a base oil (A) with a first phosphorus compound (B). A refrigerator mixture composition includes the refrigerator oil composition and a refrigerant.

The invention provides a grease composition for a speed reducer part of an on-vehicle electric component, the grease composition containing a base oil and a thickener, wherein the base oil is poly-α-olefin or a mixed oil of poly-α-olefin and mineral oil having a kinematic viscosity of 4 to 19 mm.sup.2/s at 100° C. and a pour point of −30° C. or lower, the thickener is a mixture of a diurea compound expressed by formula (1) and a diurea compound expressed by formula (2)

R.sub.1—NHCONH—R.sub.2—NHCONH—R.sub.1  (1)

R.sub.3—NHCONH—R.sub.2—NHCONH—R.sub.3  (2)

wherein R.sub.1 is a straight-chain alkyl group having 8 or 18 carbon atoms, R.sub.2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R.sub.3 is an aryl group having 6 to 7 carbon atoms, and a penetration of the grease composition is 220 to 280.

The invention is directed to a method for reducing low speed pre-ignition events in a spark-ignited direct injection internal combustion engine by supplying to the sump a lubricant composition which contains an oil of lubricating viscosity and an ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.

Lubricating oil composition is provided. The composition includes several components including a base oil, a primary antioxidant including alkylated diphenylamines having an alkyl group derived from a propylene tetramer; and a sulfonate detergent.

The present disclosure describes lubricant compositions effective to minimize average engine sludge through selection of lubricant additives that control the total nitrogen as well as the origin of the nitrogen in the lubricant composition. In aspects, the lubricant compositions herein include at least a base oil of lubricating viscosity, a dispersant system, and at least one antioxidant.

To provide a fluid dynamic bearing lubricating oil base oil which is within a suitable 40° C. and 100° C. kinematic viscosity range capable of achieving both energy saving and high bearing rigidity, and is excellent in viscosity index, heat resistance (evaporation resistance), and low temperature fluidity. Provided is a fluid dynamic bearing lubricating oil base oil containing a trimellitic acid triester compound represented by the following general formula (1)

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wherein R1 to R3 are the same or different and each represent a linear alkyl group having 6 to 10 carbon atoms.

To provide a fluid dynamic bearing lubricating oil base oil which is within a suitable 40° C. and 100° C. kinematic viscosity range capable of achieving both energy saving and high bearing rigidity, and is excellent in viscosity index, heat resistance (evaporation resistance), and low temperature fluidity. Provided is a fluid dynamic bearing lubricating oil base oil containing an isophthalic acid diester compound represented by the following general formula (1)

##STR00001## wherein R1 and R2 are the same or different and each represent a linear alkyl group having 6 to 10 carbon atoms.

The present invention relates to a lubricating oil composition containing: (A) a poly-α-olefin base oil obtained by using a metallocene catalyst; (B) a mineral oil-based base oil exhibiting a distillation curve with a temperature gradient Δ|Dt| of distillation temperature between two points 2.0 vol % and 5.0 vol % of distillation amount being 6.8° C./vol % or less; and (C) an ester-based base oil in an amount of 6% by mass or more based on a total amount of the composition.

A lubricating oil composition containing a phosphite ester derivative (A) having at least one alkyl group having 1 to 20 carbon atoms in which one —CH.sub.2— group is substituted with a —S— group, and a thiadiazole derivative (B). A method of lubricating an electric drive unit with the lubricating oil composition and an electric drive unit including the lubricating oil composition.

A working fluid composition for a refrigerating machine, containing: a refrigerant containing trifluoroiodomethane; and a refrigerating machine oil containing a complex ester synthesized from a polyhydric alcohol, a polybasic acid, and at least one selected from a monohydric alcohol and a monocarboxylic fatty acid.