Patent ID: 8754018

Claim:
A method of reducing the temperature in a lubricant oil composition, comprising: adding 4.9 to 27 wt % of at least one polyalkyl ester having a specific viscosity η sp/c , measured at 25° C. in chloroform, of between 17 and 25 ml/g, to a lubricant oil composition, wherein said lubricant oil composition is a class ISO 46 or ISO 68 fluid; wherein the at least one polyalkyl ester is prepared by polymerization of a monomer composition which consists of a) from 13 to 25% by weight of methylmethacrylate, based on the weight of the monomer composition, and b) from 75 to 87% by weight of a C 12 -C 18 alkyl methacrylate, based on the weight of the monomer composition, wherein the lubricant oil composition, by virtue of addition of said at least one polyalkyl ester, has a hydraulic performance P a at a temperature T 1 +x, where T 1 is greater than or equal to 20° C. and x is greater than or equal to 5° C., which is at least as high as the performance of the hydraulic line P b of the hydraulic fluid without addition of polyalkyl ester at the temperature T 1 , wherein said hydraulic performance P a is measured at temperatures of between 65 and 85° C.