| 摘要 |
PROBLEM TO BE SOLVED: To provide a viscosity index improver which has excellent shear stability of a lubricating oil composition and low HTHS viscosity of the lubricant composition and hardly increases low-temperature viscosity of the lubricating oil composition.SOLUTION: There is provided a lubricating oil composition comprising a viscosity index improver and a lubricating oil base oil, wherein the viscosity index improver is a (co)polymer (A) having one or more monomers selected from the group consisting of a monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) as constituent monomers, the lubricating oil base oil has a dynamic viscosity at 100°C of 2.0 to 4.5 mm/s and a viscosity index of 95 to 180 and the lubricating oil composition satisfies the following 1 to 5. (1) 100°C kinematic viscosity: 3.0 to 8.5 mm/s, (2) HTHS viscosity at 150°C: 1.4 to 3.1 mPa s, (3) HTHS viscosity at 150°C/HTHS viscosity at 100°C≥0.50, (4) VI/HTHS viscosity at 100°C≥45, and (5)PSSI≤30.SELECTED DRAWING: None |
