Lubricant base oil and lubricant composition for an internal combustion engine and lubricant composition for a driving force transmitting device

摘要

The lubricating base oil of the invention is characterized by satisfying at least one of the following conditions (a) or (b).
(a) A saturated compound content of 95 % by mass or greater, and a proportion of 0.1-10 % by mass of cyclic saturated compounds among the saturated compounds.
(b) The condition represented by the following formula (1). 1.435 ‰ n 20 - 0.002 × kv �¢ 100 ‰ 1.450
wherein n 20 represents the refractive index of the lubricating base oil at 20°C, and kv100 represents the kinematic viscosity (mm 2 /s) of the lubricating base oil at 100°C.