| abstract |
A biodegradable lubricating oil composition includes (A) an ester being obtained by reacting a saturated aliphatic carboxylic acid, a straight-chain aliphatic dicarboxylic acid and a polyhydric alcohol together, the ester having a kinematic viscosity in a range from 400 mm 2 /s to 1000 mm 2 /s at 40 degrees C. and an acid value of 0.5 mgKOH/g or less; (B) an ester being obtained by reacting a straight-chain saturated aliphatic carboxylic acid with a polyhydric alcohol, the ester having an acid value of 0.5 mgKOH/g or less; and (C) a phosphate amine salt being obtained by reacting an acidic phosphate with an alkylamine. |