Provided is a lubricating oil composition containing a mineral base oil (A) having a temperature gradient Δ|Dt| of a distillation temperature between two points of a distillation amount of 2.0% by volume and a distillation amount of 5.0% by volume in a distillation curve of 6.8° C./% by volume or less, and an antioxidant (B) containing an amine-based antioxidant (B1), a phenol-based antioxidant (B2), and a phosphorus-based antioxidant (B3), wherein the content of the component (B3) is 0.06 to 1.0% by mass based on the total amount of the lubricating oil composition. The lubricating oil composition is a long-life lubricating oil composition that maintains excellent oxidation stability even for long-term use in a high-temperature environment, and has a high effect of suppressing the generation of sludge for a long period of time.

Certain citric esters and amides, and certain mixtures thereof, e.g., mixtures comprising citrate oligomers, exhibit excellent anti-wear activity in lubricants. Many of these compounds or mixtures of compounds also exhibit a high degree of anti-wear synergy in combination with zinc dihydrocarbyldithiophosphates. The compounds of the invention are thus valuable tools that can allow one to reduce the amounts of zinc, and phosphates, that are used in the lubricant without sacrificing anti-wear performance.

The present disclosure relates to methods of lubricating an electric or a hybrid-electric transmission using a lubricant including a solvent system with a blend of one or more base oils with a branched diester and one or more poly(meth)acrylate copolymers, transmissions therefor, and lubricating compositions suitable for such applications that exhibit good lubricant properties, good electrical properties, and good cooling efficiency at the same time.

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 lubricant, including, by weight: 80-85 parts of a base oil; 1-2 parts of a methyl-silicone oil; 1-2 parts of polymethacrylate; 2-4 parts of pentaerythritol polyisobutylene succinate; 1-2 parts of di-n-butyl phosphite; 2-3 parts of butylhydroxytoluene; 2-4 parts of an ethylene-propylene copolymer; 1-2 parts of an alkenyl succinate; and 3-5 parts of copper nanoparticles. A method of preparing the lubricant includes: adding the base oil, the methyl-silicone oil, the polymethacrylate, the ethylene-propylene copolymer, the butylhydroxytoluene, the alkenyl succinate to a reactor, and stirring a resulting first mixture under normal temperature and pressure at 300-400 rpm for 3-4 hours, to yield a primary product; and adding the di-n-butyl phosphite, the pentaerythritol polyisobutylene succinate, and the copper nanoparticles to the primary product, and stirring a resulting second mixture at 150-250 rpm for 2-2.5 hours.

The present invention provides a lubricating oil composition for automatic transmissions which comprises: 55 to 85 mass % of a Fischer-Tropsch synthetic oil with a kinematic viscosity at 100° C. of 2 to 4 mm2/s as a low-viscosity base oil; 1 to 10 mass % of an olefin copolymer 5 with a kinematic viscosity at 100° C. of 150 to 1,000 mm2/s as a high-viscosity base oil; and a polymethacrylate with a weight-average molecular weight of 10,000 to 50,000. This lubricating oil composition is such that the viscosity index of the composition is not 10 less than 190, the Brookfield viscosity is not more than 6,000 mPa.Math.s at low temperature (−40° C.), the kinematic viscosity at 100° C. is 6 to 7 mm2/s, and the rate of reduction of the kinematic viscosity after a KRL shear stability test (60° C., 20 hr) is kept to within not more 15 than 3%.

The present invention provides a lubricating oil composition for automatic transmissions which comprises: 55 to 85 mass % of a Fischer-Tropsch synthetic oil with a kinematic viscosity at 100° C. of 2 to 4 mm2/s as a low-viscosity base oil; 1 to 10 mass % of an olefin copolymer 5 with a kinematic viscosity at 100° C. of 150 to 1,000 mm2/s as a high-viscosity base oil; and a polymethacrylate with a weight-average molecular weight of 10,000 to 50,000. This lubricating oil composition is such that the viscosity index of the composition is not 10 less than 190, the Brookfield viscosity is not more than 6,000 mPa.Math.s at low temperature (−40° C.), the kinematic viscosity at 100° C. is 6 to 7 mm2/s, and the rate of reduction of the kinematic viscosity after a KRL shear stability test (60° C., 20 hr) is kept to within not more 15 than 3%.

A lubricant composition includes a polyalkylene glycol base oil component in an amount of at least about 60 parts by weight based on 100 parts by weight of the lubricant composition. The lubricant composition has a kinematic viscosity at 100° C. of from about 4 to about 50 cSt and a kinematic viscosity at 40° C. of from about 20 to about 700 cSt, each measured in accordance with ASTM D445.

Described herein is a stabilized lubricant composition for use in steel casting, in particular in continuous casting processes. In particular, the lubricant composition for processes for producing steel by continuous casting includes a dispersion of a lubricant powder, for an ingot mold, in continuous casting, in an oily liquid means, and a stabilization additive, characterized in that it has the following shear thinning index values:

TABLE-US-00001 RVT 0.1/1 1/10 10/100 100/1000 STI 3.0-7.5 2.0-6.5 1.0-3.0 0.5-2.0 wherein RVT is the ratio between two different shear speeds and STI is the shear thinning index corresponding to the RVT values.

Provided are: a lubricating oil composition containing a mineral oil (A) having a kinematic viscosity at 40° C. of 5 to 15 mm.sup.2/s and a flash point of 180° C. or higher, a synthetic oil (B) having a kinematic viscosity at 40° C. of 5 to 15 mm.sup.2/s and a flash point of 190° C. or higher, an amide compound (C) and a polyol ester compound (D), which has a low viscosity and fuel saving performance, which can be used in high-temperature environments, and which has excellent gear anti-seizing property and anti-shudder performance; and a lubrication method and a transmission using the lubricating oil composition.