| abstract |
A lubricating oil composition for a power transmission system, which is excellent in both of low-temperature viscosity property and shear stability, is provided. The viscosity modifier of a lubricating oil for a power transmission system according to the present invention comprises an ethylene/α-olefin copolymer (B) having the properties: (B1) an ethylene content in the range of 70 to 85% by mol, (B2) an intrinsic viscosity [η] in the range of 0.2 to 1.0 dl/g, (B3) Mw/Mn not more than 2.4, and (B4) a melting point, as measured by DSC, not higher than 60° C., or no melting point observed. |