Lubricating oil composition for transmissions

摘要

Lubricating oil compositions for transmissions comprise (A) a mineral lubricating oil having a kinematic viscosity of from 2.3 to 3.4 mm<2>/s and a %Cp of 7.0 or higher defined by ASTM D 3238, as a base oil, (B) a phosphorus compound in an amount of from 0.025 to 0.05 percent by mass in terms of phosphorus based on the total mass of the composition, and (C) a viscosity index improver in such an amount that the composition has a kinematic viscosity of from 5.0 to 6.0 mm<2>/s, sulfur being contained in an amount of 0.15 percent by mass or less in the composition. The lubricating oil compositions are excellent in fuel efficiency and capable of improving the durabilities of gears and clutches, leading to long lasting gear change characteristics.