POLYOL ESTER-BASED LUBRICATING OIL COMPOSITION

摘要

PROBLEM TO BE SOLVED: To obtain a composition having a kinematic viscosity in a specified range and excellent flame retardancy and oxidation stability by making a base oil comprising an unsaturated fatty acid polyol ester contain a phenol/α- naphthylamine dehydration condensate in a specified ratio. SOLUTION: To the base oil comprising an unsaturated fatty acid polyol ester, 0.8-5 mass % antioxidant such as a phenol/α-naphthylamine dehydration condensate and further 0.01-30 mass % rust preventive, 0.01-5 mass % corrosion preventive, 0.1-1 mass % other antioxidants and 10-100 ppm of an antifoam are added to obtain the lubricating oil composition having a kinematic viscosity (at 40 deg.C) of 10-150 mm<2> /s. The unsaturated fatty acid polyol ester is exemplified by an ester obtained by reacting an 8-32C unsaturated monocarboxylic acid with a 2-10C polyol and having a kinematic viscosity (at 40 deg.C) of 20-100 mm<2> /s or a complex ester obtained by reacting an unsaturated monocarboxylic acid and an 8-54C unsaturated polycarboxylic acid with a polyol and having a kinematic viscosity (at 40 deg.C) of 40-1,000 mm<2> /s.