Lubricating oil composition

Abstract

[Problem]To provide a lubricating oil composition capable of attaining high-level fuel efficiency, durability and piston detergency in internal-combustion engines.[Means for Resolution]The lubricating oil composition according to the present invention contains a viscosity index improver and a metallic detergent in at least one base oil selected from mineral oils and synthetic oils therein, wherein the viscosity index improver contains a polymethacrylate viscosity index improver and an olefin copolymer viscosity index improver, the polymethacrylate viscosity index improver is contained in an amount of from 3.0% by mass to 9.5% by mass based on the total amount of the lubricating oil composition, the metallic detergent is at least one selected from calcium sulfonate, calcium phenate and calcium salicylate, the calcium amount derived from the metallic detergent is from 500 ppm to 1500 ppm based on the total amount of the lubricating oil composition, the high-temperature high-shear viscosity at 150° C. of the lubricating oil composition is 2.6 mPa·s or more, the high-temperature high-shear viscosity at 80° C. of the lubricating oil composition is 7.8 mPa·s or less, and the ratio of the high-temperature high-shear viscosity at 100° C. of the lubricating oil composition to the high-temperature high-shear viscosity at 150° C. thereof is 2.05 or less.

Description

TECHNICAL FIELD[0001]The present invention relates to a lubricating oil composition for use in internal-combustion engines such as diesel engines, gasoline engines, gas engines, engines for hybrid cars, etc.BACKGROUND ART[0002]At present, with the surge of the consciousness for the environment on the earth scale, implementation of measures against environmental issues such as global warming, etc., as well as against depletion of oil resources is desired. In vehicle-related fields, emission control, development of fuel-efficient automobiles and others are much more desired.[0003]For measures for emission control, employed are exhaust gas filters such as diesel particulate filters, gasoline particulate filters and the like for removing metal fractions (also referred to as ash fractions) derived from lubricating oil compositions used in internal-combustion engines, and exhaust-gas aftertreatment devices such as ternary catalysts, oxidation catalysts, etc.[0004]In this case, it is known...

AI Technical Summary

Benefits of technology

[0025]According to the present invention, there can be provided a lubricating oil composition capable of attaining fuel efficiency, durability and piston detergency in internal-combustion engines at a high level.

Problems solved by technology

In this case, it is known that metal fractions mix in exhaust gas streams and deposit in aftertreatment devices to lower the removal efficiency.

However, a too low HTHS viscosity increases a wear amount.

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