Lubricant composition and method for producing same

The method for producing a lubricating oil composition comprising:

• blending a first lubricating base oil component having a urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 14-25 mm2/s and a viscosity index of 120 or higher, a second lubricating base oil component having a kinematic viscosity at 40° C. of less than 14 mm2/s, and a viscosity index improver, to obtain a lubricating base oil wherein the content of the first lubricating base oil component is 10-99% by mass and the content of the second lubricating base oil component is 1-50% by mass, based on the total amount of the lubricating base oil;
• and
• adding a viscosity index improver to the lubricating base oil, to obtain a lubricating oil composition having a kinematic viscosity at 100° C. of 4-12 mm2/s and a viscosity index of 200-350.

A method for producing a lubricating oil composition for an internal combustion engine comprising:

• blending a first lubricating base oil component having a urea adduct value of not greater than 4% by mass, a viscosity index of 100 or higher and a kinematic viscosity at 100° C. of at least 3.5 mm2/s and less than 4.5 mm2/s, and a second lubricating base oil component having a urea adduct value of not greater than 4% by mass, a viscosity index of 120 or greater and a kinematic viscosity at 100° C. of 4.5-20 mm2/s, to obtain a lubricating base oil having a viscosity index of 100 or higher, an initial boiling point of not higher than 400° C., a 90% distillation temperature of 470° C. or higher and a difference between the 90% distillation temperature and a 10% distillation temperature of at least 70° C., and
• adding an ashless antioxidant containing no sulfur as a constituent element, and at least one selected from among ashless antioxidants containing sulfur as a constituent element and organic molybdenum compounds to the lubricating base oil.