LUBRICATING OIL COMPOSITION AND METHOD FOR PRODUCTION THEREOF

摘要

In a lubricating oil composition, an efficient defoaming action must be exerted both against bubbles on the oil surface and against bubbles within the oil. To this end, the present invention provides a lubricating oil composition, comprising polydimethylsiloxane having a kinematic viscosity of from 10 000 to 60 000 mm<SUP>2</SUP>/sec at 25°C in an amount of from 0.1 to 30 ppm, preferably from 0.1 to 10 ppm, calculated as content of Si, and a polyacrylate defoamant having a weight average molecular weight of from 4 000 to 150 000 in an amount of at least 60 times the aforesaid polydimethylsiloxane, calculated as content of Si (ppm).