A lubricant composition includes a base oil present in an amount of greater than 70 parts by weight per 100 parts by weight of the lubricant composition and an antioxidant. The antioxidant has the structure: wherein each X is independently CH or N, so long as at least one X is N, wherein Y is CRR, NR, PR, S, or O, each R, R and R is independently H, alkyl or aryl, and R is alkyl, aryl, alkoxy or aryloxy. Each A is independently an electron donating group. The electron donating group (1) has an atom having at least one lone pair of electrons that is bonded directly to the aromatic ring, (2) is an aryl or alkyl group, or (3) is a hydrogen atom.

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A lubricant composition includes a base oil present in an amount of greater than 70 parts by weight per 100 parts by weight of the lubricant composition and an antioxidant. The antioxidant has the structure: wherein each X is independently CH or N, so long as at least one X is N, wherein Y is CRR, NR, PR, S, or O, each R, R and R is independently H, alkyl or aryl, and R is alkyl, aryl, alkoxy or aryloxy. Each A is independently an electron donating group. The electron donating group (1) has an atom having at least one lone pair of electrons that is bonded directly to the aromatic ring, (2) is an aryl or alkyl group, or (3) is a hydrogen atom.

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The invention provides a grease composition containing a base oil, a thickener, and an anti-flaking additive such as a compound represented by, for example, formula (1-1), which grease composition can prevent the white layer flaking of the rolling bearings. (In the formula, R1 and R4 are each independently a straight-chain or branched alkyl or alkenyl group having 1 to 20 carbon atoms.) ##STR00001##

The invention provides a grease composition containing a base oil, a thickener, and an anti-flaking additive such as a compound represented by, for example, formula (1-1), which grease composition can prevent the white layer flaking of the rolling bearings. (In the formula, R1 and R4 are each independently a straight-chain or branched alkyl or alkenyl group having 1 to 20 carbon atoms.) ##STR00001##

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.

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.

A fluid contains a base oil and an antioxidant, the base oil consisting of sulfur-containing polyalkylene glycol where greater than 80 weight-percent of the fluid is a sulfur-containing polyalkylene glycol and less than one weight-percent of the fluid is water, with weight percent based on total fluid weight an wherein the sulfur-containing polyalkylene glycol is free of oxygen bound directly to sulfur.

A fluid contains a base oil and an antioxidant, the base oil consisting of sulfur-containing polyalkylene glycol where greater than 80 weight-percent of the fluid is a sulfur-containing polyalkylene glycol and less than one weight-percent of the fluid is water, with weight percent based on total fluid weight an wherein the sulfur-containing polyalkylene glycol is free of oxygen bound directly to sulfur.

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.)

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.)