Patent ID: 8906833

Claim:
A lubricant composition comprising: (A) a lubricant base oil consisting of, based on the total amount of said base oil, (A-i) 70 to 92 mass % of a lubricant base oil having a 100° C. kinematic viscosity of not less than 1 and less than 5 mm 2 /s, and (A-ii) 8 to 30 mass % of a lubricant base oil having a 100° C. kinematic viscosity of 5.7 to 10 mm 2 /s, and (B) a poly(meth)acrylate viscosity index improver having a weight average molecular weight of not less than 10000, and a ratio of the weight average molecular weight to a permanent shear stability index of not lower than 0.8×10 4 , said viscosity index improver (B) having 1 to 70 mol % of one or more (meth)acrylate structural units represented by formula (I): wherein R 1 stands for a hydrogen atom or a methyl group, and R 2 stands for a straight or branched hydrocarbon group having not less than 16 carbon atoms, wherein said composition comprises 0.1 to 50 mass % of said viscosity index improver (B) based on a total amount of the composition, and wherein said composition has a 100° C. kinematic viscosity of 3 to 15 mm 2 /s, a viscosity index of 190 to 300, a 150° C. high-temperature, high shear viscosity (HTHS viscosity) of 2.0 to 2.8 mPa·s, and a ratio of a 150° C. HTHS viscosity to a 100° C. HTHS viscosity of not less than 0.51.