Lubricating oil composition

Abstract

A lubricating oil composition which exceeds the fuel saving performance of a conventional low viscosity lubricating oil composition, contains (A) a lubricating base oil having a % CA of 2 or less, adjusted to a 100° C. kinematic viscosity of 1.5 to 4.5 mm2 / s and (B) a viscosity index improver including (B1) a poly(meth)acrylate having a weight-average molecular weight of 50,000 or less in an amount of 1 to 10 percent by mass and (B2) a poly(meth)acrylate having a weight-average molecular weight of 100,000 to 250,000 in an amount of 0.1 to 5 percent by mass of the total composition. The composition has a 80° C. high-shear viscosity (Vs: mPa·s) and a 80° C. kinematic viscosity (Vk: mm2 / s) ratio (Vs / Vk) of less than 1, a coefficient of traction of 0.02 or less at 40° C., an average speed of 3.0 m / s, a slip ratio of 10%, and a contact pressure of 0.4 GPa.

Description

TECHNICAL FIELD [0001]The present invention relates to lubricating oil compositions, more specifically to those having an enhanced fuel saving performance, suitable for automobile automatic transmissions, manual transmissions, and continuously variable transmissions.BACKGROUND ART [0002]Recently, energy saving in automobiles and construction or agricultural machinery, i.e., fuel saving has become an urgent need in order to deal with environmental issues such as reduction in carbon dioxide emissions, and units such as engines, transmissions, final reduction gears, compressors, or hydraulic power units have been strongly demanded to contribute to energy saving. Consequently, the lubricating oils used in these units are required to be reduced in stir resistance and frictional resistance more than before.[0003]Reduction of the viscosity of a lubricating oil can be pointed out as an effective energy saving means. For example, an automobile automatic transmission or continuously variable ...

AI Technical Summary

Benefits of technology

The present invention relates to a lubricating oil composition that can improve engine fuel efficiency. The oil composition features a specific lubricating base oil that has a low resistance to lubrication, making it suitable for use in automobile transmissions. The base oil can be either mineral or synthetic, with a specific viscosity range. The composition also includes specific additives that further improve fuel efficiency. Overall, this lubricating oil can improve engine performance by reducing friction and increasing fuel efficiency.

Problems solved by technology

However, as described above, the lubricating oil used in these transmissions is also used as a medium for a hydraulic control system and thus would have problems that it would fail to generate sufficient hydraulic pressure due to the leakage from the oil pump or control valve if it is excessively reduced in viscosity.

However, the oil has been unable to meet the recent further fuel saving demand.

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