LUBRICANT OIL COMPOSITION

摘要

As a lubricant oil composition which has excellent thermal stability, water resistance, extreme pressure performance and abrasion resistance and is safe for the environment, a lubricant oil composition is provided which contains a lubricant oil base oil and also contains a phosphorus compound represented by formula (1) in an amount of 10 to 10000 ppm by mass in terms of phosphorus content relative to the whole amount of the composition. (In the formula, R1 and R2 independently represent a hydrocarbon group having 2 to 18 carbon atoms; R3 represents a hydrocarbon group having 1 to 4 carbon atoms; and R4 represents a hydrogen atom or a hydrocarbon group having 1 or more carbon atoms.)