Grease composition

A grease composition comprising:

• (a) a base oil at 70 to 90% by mass based on a total mass of the composition;
• (b) a thickener comprising a urea compound at 5 to 25% by mass based on the total mass of the composition;
• (c) an amine antioxidant at 0.5 to 5% by mass based on the total mass of the composition;
• and
• (d) a quinoline antioxidant at 0.5 to 5% by mass based on the total mass of the composition,
• wherein the base oil comprises 10 to 20% by mass of a highly refined mineral oil having a pour point of −35° C. or lower based on a total mass of the base oil,
• wherein the urea compound is a diurea compound represented by the following formula (1):
• where R2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and one of R1 and R3 is a saturated or unsaturated alkyl group having 6 to 30 carbon atoms, and the other is a cyclohexyl group,
• wherein the (c) amine antioxidant is alkyldiphenyl amine or phenyl-α-naphthyl amine, and
• wherein the (d) quinoline antioxidant is at least one quinoline antioxidant selected from the group consisting of 2,2,4-trimethyl-1,2-dihydroquinoline, 2-methyl-2,4-diethyl-1,2-dihydroquinoline, 2,2,4,6-tetramethyl-1,2-dihydroquinoline, 2,2,4,7-tetramethyl-1,2-dihydroquinoline, 6,6′-bis(2,2,4-trimethyl-1,2-dihydroquinoline), and homopolymers thereof.