Lubricating Oil Composition

Abstract

Disclosed is a lubricating oil composition comprising: a lubricating base oil comprising 0.5% to 70% by mass of an ester base oil based on the total amount of the lubricating base oil, and having a kinematic viscosity at 40° C. of 18 to 28 mm²/s; and an organic molybdenum compound in an amount of 100 to 1000 mass ppm in terms of the molybdenum element based on the total amount of the lubricating oil composition, wherein the lubricating oil composition has a kinematic viscosity at 40° C. of 50 mm²/s or less.

Description

TECHNICAL FIELD[0001]The present invention relates to a lubricating oil composition.BACKGROUND ART[0002]In recent years, in order to cope with environmental problems such as reduction in carbon dioxide emission, the saving of energy in automobiles, construction machineries, agricultural machineries, etc., namely, fuel saving has become an urgent task, and thus, it has been strongly desired that devices such as engines, transmissions, final drive gears, compressors or hydraulic systems contribute to such saving of energy. As such, lubricating oil used in these devices has been required to reduce stirring resistance and rotational resistance, in comparison to the conventional oil.[0003]As a means for fuel saving in transmissions and final drive gears, reduction in the viscosity of lubricating oil is applied. For example, among transmissions, automatic transmissions and continuously variable transmissions for use in automobiles have a torque converter, a wet clutch, a gear bearing mech...

AI Technical Summary

Benefits of technology

[0017]According to the present invention, there is provided a lubricating oil composition, which has sufficient extreme pressure properties and wear resistance, and further reduces a metal-to-metal friction coefficient. Therefore, when the lubricating oil composition of the present invention is applied to an automotive manual transmission, an automatic transmission or a continuously variable transmission, or to an industrial gear system, it can achieve fuel saving, while maintaining properties necessary as a gear oil, and particularly, as a hypoid gear oil.

Problems solved by technology

As such, lubricating oil used in these devices has been required to reduce stirring resistance and rotational resistance, in comparison to the conventional oil.

However, in order to reduce the viscosity of lubricating oil and to achieve a high viscosity index, if the viscosity of base oil is decreased and a large amount of viscosity index improver is blended into the oil, a reduction in the oil film thickness, which is competing performance, causes a reduction in extreme pressure properties and wear resistance, and as a result, seizure and the like may occur, so that defects and the like would occur in transmissions, etc.

Moreover, if the amounts of a sulfur extreme pressure agent and a phosphorus-sulfur extreme pressure agent are increased to improve extreme pressure properties, oxidation stability would be significantly deteriorated.

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