| abstract |
The lubricant base oil of the invention has excellent energy-conserving performance, low-temperature viscosity characteristics, and detergency. The composition contains: (A) a lubricant base oil composed of, based on the total base oil amount, 50 to 99.9 mass % of a lubricant base oil having a 100° C. kinematic viscosity of 1 to less than 5 mm 2 /s, and 0.1 to 50 mass % of a lubricant base oil having a 100° C. kinematic viscosity of 5 to 200 mm 2 /s, and (B) a viscosity index improver having average Mw of not less than 10000, and a Mw to PSSI ratio of not lower than 0.8×10 4 , wherein the composition contains 0.1 to 50 mass % of component (B) based on the total composition amount, and has a 100° C. kinematic viscosity of 3 to 15 mm 2 /s and a 150° C. to 100° C. HTHS viscosity ratio of not less than 0.50. |