US Patent 8999904 Lubricant oil composition and method for making the same

The lubricating oil composition of the invention comprises a lubricating base oil with a kinematic viscosity at 100° C. of 1-20 mm2/s, and a viscosity index improver having a ratio M1/M2 of 0.20 or greater, between the total area of the peaks between chemical shifts of 36-38 ppm M1 and the total area of the peaks between chemical shifts of 64-66 ppm M2, with respect to the total area of all of the peaks, in the spectrum obtained by 13C-NMR. The lubricating oil composition of the invention has excellent effects, with a sufficiently high HTHS viscosity at 150° C., and a sufficiently low kinematic viscosity at 40° C., a sufficiently low kinematic viscosity at 100° C. and a sufficiently low HTHS viscosity at 100° C.