| 摘要 |
[Problem] To provide a lubricating oil composition capable of attaining high-level fuel efficiency, durability and piston detergency in internal-combustion engines. [Means for Resolution] The lubricating oil composition according to the present invention contains a viscosity index improver and a metallic detergent in at least one base oil selected from mineral oils and synthetic oils therein, wherein the viscosity index improver contains a polymethacrylate viscosity index improver and an olefin copolymer viscosity index improver, the polymethacrylate viscosity index improver is contained in an amount of from 3.0% by mass to 9.5% by mass based on the total amount of the lubricating oil composition, the metallic detergent is at least one selected from calcium sulfonate, calcium phenate and calcium salicylate, the calcium amount derived from the metallic detergent is from 500 ppm to 1500 ppm based on the total amount of the lubricating oil composition, the high-temperature high-shear viscosity at 150°C of the lubricating oil composition is 2.6 mPa·s or more, the high-temperature high-shear viscosity at 80°C of the lubricating oil composition is 7.8 mPa·s or less, and the ratio of the high-temperature high-shear viscosity at 100°C of the lubricating oil composition to the high-temperature high-shear viscosity at 150°C thereof is 2.05 or less. |
