Patent ID: 8247360

Claim:
A heat treating oil composition comprising: a lubricating base oil having % C A of not more than 2, % C p /% C N of not less than 6, % C N of 7 to 13, a sulfur content of not more than 100 ppm by mass, and an iodine value of not more than 2.5, wherein the content of the saturated components in the lubricating base oil is not less than 95% by mass based on the total amount of the lubricating base oil and wherein the ratio M A /M B of the mass of monocyclic saturated components M A to the mass of bi- or more cyclic saturated components M B in the saturated cyclic components is not more than 3; and at least one cooling property improver selected from copolymers of ethylene and An α-olefin having 3 to 20 carbon atoms, and asphalts and products having insoluble matters removed from asphalts.