LUBRICATING OIL COMPOSITION

摘要

The present invention aims to offer a lubricating oil composition which is able to maintain in the lubricating oil composition a defoaming effect and excellent defoaming properties with regard to the foam on the surface of the oil which occurs because of high-speed churning. To this end the present invention provides a lubricating oil composition comprising a base oil and polydimethylsiloxanes wherein the molecular weight distribution of the polydimethylsiloxanes as measured by gel permeation chromatography (GPC) is such that the content of the log M = 4.2 portion converted to polystyrene is not less than 84 % and the content of the log M = 3.1 portion is not more than 3 %, and wherein kinetic viscosity at 25 °C is from 10,000 to 60,000 mm<SUP>2</SUP>/s.