The present invention relates to a lubricating oil composition containing a base oil (A), a molybdenum dithiocarbamate (B), an ester-based ashless friction modifier (C), and a metal salicylate (D), wherein the content of a molybdenum atom derived from the molybdenum dithiocarbamate (B) is 650 ppm by mass or more on the basis of the whole amount of the lubricating oil composition; a content ratio [C/B.sub.Mo] of the ester-based ashless friction modifier (C) to a molybdenum atom derived from the molybdenum dithiocarbamate (B) is 5.0 to 10 in terms of a mass ratio; the content of a salicylate soap group derived from the metal salicylate (D) is 0.50% by mass or more on the basis of the whole amount of the lubricating oil composition; and a kinematic viscosity at 100 C. is 4.0 mm.sup.2/s or more and less than 9.3 mm.sup.2/s, and a high-temperature high-shear viscosity at 150 C. is 1.7 mPa.Math.s or more and less than 2.9 mPa.Math.s. In accordance with the present invention, a viscosity-reduced lubricating oil composition in which nonetheless a molybdenum dithiocarbamate and an ashless friction modifier are jointly used, not only friction can be reduced early after commencement of lubrication, but also such a state can be maintained, is provided.

The present invention relates to a lubricating oil composition containing a base oil (A), a molybdenum dithiocarbamate (B), an ester-based ashless friction modifier (C), and a metal salicylate (D), wherein the content of a molybdenum atom derived from the molybdenum dithiocarbamate (B) is 650 ppm by mass or more on the basis of the whole amount of the lubricating oil composition; a content ratio [C/B.sub.Mo] of the ester-based ashless friction modifier (C) to a molybdenum atom derived from the molybdenum dithiocarbamate (B) is 5.0 to 10 in terms of a mass ratio; the content of a salicylate soap group derived from the metal salicylate (D) is 0.50% by mass or more on the basis of the whole amount of the lubricating oil composition; and a kinematic viscosity at 100 C. is 4.0 mm.sup.2/s or more and less than 9.3 mm.sup.2/s, and a high-temperature high-shear viscosity at 150 C. is 1.7 mPa.Math.s or more and less than 2.9 mPa.Math.s. In accordance with the present invention, a viscosity-reduced lubricating oil composition in which nonetheless a molybdenum dithiocarbamate and an ashless friction modifier are jointly used, not only friction can be reduced early after commencement of lubrication, but also such a state can be maintained, is provided.

The use of polyalkylenyl succinic anhydrides to stabilize an additive concentrate which includes a salicylate detergent and a nitrogen-free ashless organic friction modifier.

The use of polyalkylenyl succinic anhydrides to stabilize an additive concentrate which includes a salicylate detergent and a nitrogen-free ashless organic friction modifier.

The present application relates to the use, in a lubricant composition comprising at least one base oil, of 2 to 12% by weight, relative to the weight of said lubricant composition, of an ester that has a viscosity at 100 C. of between 200 and 1000 cSt, for the purpose of improving the cleanliness of an engine.

A method for improving wear control of a steel surface lubricated with a lubricating oil through the generation of thick tribofilms. The method includes: (i) using as the lubricating oil a formulated oil, the formulated oil having a composition comprising at least one lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; and (ii) forming a tribofilm on the steel surface. In time-step tribofilm formation measurements of the lubricating oil by a mini-traction machine (MTM) at constant slide-to-roll ratio (SRR), the saturation traction coefficient (f.sub.s), which correlates to tribofilm thickness on the steel surface, is greater than about 0.11. In the method of this disclosure, elongation of timing chain due to wear of chain link pins is less than about 0.07%, as determined by Ford Chain Wear (FCW) test conducted in accordance with ILSAC GF-6 specification. The lubricating oils are useful in internal combustion engines.

A method for improving wear control of a steel surface lubricated with a lubricating oil through the generation of thick tribofilms. The method includes: (i) using as the lubricating oil a formulated oil, the formulated oil having a composition comprising at least one lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; and (ii) forming a tribofilm on the steel surface. In time-step tribofilm formation measurements of the lubricating oil by a mini-traction machine (MTM) at constant slide-to-roll ratio (SRR), the saturation traction coefficient (f.sub.s), which correlates to tribofilm thickness on the steel surface, is greater than about 0.11. In the method of this disclosure, elongation of timing chain due to wear of chain link pins is less than about 0.07%, as determined by Ford Chain Wear (FCW) test conducted in accordance with ILSAC GF-6 specification. The lubricating oils are useful in internal combustion engines.

Provided is a grease composition for a ball joint that can reduce the wear of a ball seat at a slide region and also has excellent compatibility with a dust cover. The grease composition for a ball joint comprises a base oil, a thickener, and an additive. The base oil contains an ethylene--olefin copolymer and the kinetic viscosity of the base oil at 40 C. is 2,000 to 6,000 mm.sup.2 /s. The additive contains a polar wax (e.g., monoamide wax or ester wax).

The invention relates to industrial gear oil compositions that have been specially designed to have improved storage stability and/or paint compatibility and/or seal compatibility. This improvement is achieved while maintaining good performance in other areas. These improvements are particularly relevant to synthetic lubricants, such as those made with polyalphaolefin (PAO) base oils. This balance of properties has been difficult to achieve in synthetic compositions where problems in the areas of storage stability, paint compatibility and/or seal compatibility of become more pronounced. The invention also relates to processes of making such compositions and methods of using the same.

The invention relates to industrial gear oil compositions that have been specially designed to have improved storage stability and/or paint compatibility and/or seal compatibility. This improvement is achieved while maintaining good performance in other areas. These improvements are particularly relevant to synthetic lubricants, such as those made with polyalphaolefin (PAO) base oils. This balance of properties has been difficult to achieve in synthetic compositions where problems in the areas of storage stability, paint compatibility and/or seal compatibility of become more pronounced. The invention also relates to processes of making such compositions and methods of using the same.