Lubricating oil composition for automobile engine lubrication

Abstract

Provided is a lubricating oil composition that is highly fuel-efficient and has high wear resistance and is particularly suited for lubrication of a motorcycle four-cycle gasoline engine or a diesel engine vehicle having an exhaust gas after-treatment device. The lubricating oil composition, which is a lubricating oil composition having an SAE viscosity grade of 5W20, comprises a base oil and predetermined amounts of additive components comprising of a nitrogen-containing ash-free dispersant, an alkali earth metal-containing detergent, a phosphorus-containing anti-wear agent, an antioxidant, and a viscosity index-improving agent, wherein the viscosity index is within a range of 140 to 230, the high-shear viscosity at 150° C. is 2.9 mPa·s or higher, and the NOACK evaporation loss is 13% or less.

Description

[0001]This patent application is a Divisional of U.S. patent application Ser. No. 13 / 786,555 filed on Mar. 6, 2013, and which claims priority to Japanese Patent Application number JP 2012-51849 which was filed on Mar. 8, 2012.FIELD OF INVENTION[0002]The present invention relates to an excellent fuel-efficient, low-viscosity lubricating oil composition for an automobile engine, and in particular, relates to a lubricating oil composition for automobile engine lubrication that, while being an excellent fuel-efficient, low-viscosity lubricating oil composition for engine lubrication, also shows high wear resistance. The present invention relates to a low-viscosity lubricating oil composition that is particularly suitable for lubricating a motorcycle four-cycle gasoline engine or a diesel engine having an exhaust gas after-treatment device.BACKGROUND OF INVENTION[0003]There is an increasing demand for improved fuel efficiency in automobiles. Therefore, there is a need for an excellent fu...

AI Technical Summary

Benefits of technology

[0010]The inventors completed the present invention upon discovering that it is possible to produce a lubricating oil composition that has an SAE viscosity grade of 5W20 and yet a viscosity index within a range of 140 to 230, a high-shear (106 s−1) viscosity at 150° C. of 2.9 mPa·s or higher, a NOACK evaporation loss of 13% or less, and excellent wear resistance by using a base oil such as has been recently supplied to the market and is primarily isoparaffin, has an ultrahigh viscosity index wherein the viscosity index is within a range of approximately 133 to 160, and is obtained by hydrogenation and isomerization of a slack wax or a synthetic wax produced by the Fischer-Tropsch method and distillation and dewaxing treatment, and by optimizing the combination of additive components added to the base oil and the amount of each lubricant component. Note that lubricating oil compositions of SAE viscosity grade 5W20 are already known to have excellent fuel efficiency because they have a relatively low dynamic viscosity under temperature conditions of both low temperatures and high temperatures.

Problems solved by technology

Nevertheless, fuel-efficient gasoline engine oils for four-wheel drive vehicles having an SAE viscosity grade of 5W20 cannot be expected to have a high-temperature, high-shear viscosity that is as high as 2.6 mPa·s and therefore, there is a problem in that when used as the engine oil of a motorcycle four-cycle gasoline engine that uses engine oil for lubrication of the transmission system, there is a problem in that wear resistance is insufficient.