Lubricant oil composition and method for making the same

A method for producing a lubricating oil composition, in which:

• a first lubricating base oil component having a urea adduct value of no greater than 5% by mass, a kinematic viscosity at 40° C. of at least 14 mm2/s and no greater than 25 mm2/s and a viscosity index of 120 or greater,
• a second lubricating base oil component having a kinematic viscosity at 40° C. of 5 mm2/s or greater and less than 14 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,
• are combined to obtain a lubricating oil composition having a first lubricating base oil component content of 10-99% by mass and a second lubricating base oil component content of 1-50% by mass, based on the total weight of the lubricating base oil, and a kinematic viscosity at 100° C. of 4-12 mm2/s and a viscosity index of 200-350.