Provided is a mineral base oil having a kinematic viscosity at 40 C. of 4.0 mm.sup.2/s or more and less than 6.0 mm.sup.2/s, a kinematic viscosity at 100 C. of 1.0 mm.sup.2/s or more and less than 2.0 mm.sup.2/s, and a flash point of 140 C. or higher. A lubricating oil composition containing the mineral base oil has a high flash point while having a low viscosity and thus having excellent fuel-saving performance when used as a driving system oil and the like.

A fluid contains a base oil consisting of an alcohol-initiated polyalkylene glycol where polyalkylene glycol component is selected from a homopolymer of 1,2-butylene oxide and copolymer of 1,2-butylene oxide and propylene oxide; a glycerol-initiated unsaturated ester that is free of tertiary carbon atoms and quaternary carbon atoms; and an antioxidant.

The invention relates to phosphorous-containing compounds useful as antiwear additive components, lubricant additive compositions and lubricant compositions each comprising such compounds, methods for making and using the same, including methods of lubricating machines and machine parts and methods of extending the useful life of elastomeric seal components of such machines.

Provided is a lubricant composition which is excellent in thermal stability and chemical stability while making it possible to detect a leakage point of the lubricant composition, etc. with a fluorescent agent. The lubricant composition is one containing a base oil (A) and a fused ring compound (B) being fluorescent, having a tri- or higher fused ring, and not having nitrogen, oxygen, and sulfur in a molecule thereof, wherein the fused ring compound (B) is contained in an amount of 0.001 to 1.0% by mass on a basis of the whole amount of the lubricant composition.

There is disclosed an antifoam component for a mechanical device which includes a fluorinated poly(acrylate) copolymer. The antifoam component has improved foam performance and thermal stability in finished fluids, such as driveline fluids.

A thermodynamic cycle such as an organic Rankine cycle system, utilizing a lubricant and a working fluid, for a machine in which pressurized gaseous working fluid is expanded to a lower pressure level and the energy from the fluid expansion is transformed into mechanical rotation energy; the lubricant includes a polyalkylene glycol based lubricant composition and the working fluid includes a mixture of alcohol and water.

Provided herein are hydrocarbon mixtures with controlled structure characteristics that address the performance requirements for finished lubricants driven by the stricter environmental and fuel economy regulations. The branching characteristics of the hydrocarbon molecules are controlled to provide a composition that has a unique and superior viscosity-temperature relationship and Noack volatility. An important aspect of the present invention relates to a saturated hydrocarbon mixture with at least 80% of the molecules having an even carbon number, with the branching characteristic of BP/BI in the range 0.6037 (Internal alkyl branching)+2.0, where on average at least 0.3 to 1.5 of the internal methyl branches are located more than 4 carbons away from the terminal carbon when analyzed by carbon NMR. The saturated hydrocarbon mixture with such unique branching structure consistently exhibits a stand out performance in the cold crank simulated viscosity (CCS) vs Noack volatility relationship, which allows for the formulation of lower viscosity engine oils with improved fuel economies.

Disclosed are solvency enhancer compositions, for example, as additives to lubricating oils and as formulated in lubricating oil compositions and associated methods of preparation and use thereof. The compositions and methods can dissolve at least one of oxidation products and other organic polar compounds, due to lubricant degradation, formed and suspended in oil compositions including adding an effective amount of a solvency enhancer to the oils, wherein the solvency enhancer includes Guerbet alcohols. Further described are methods for dissolving organic deposits in an oil system including adding an effective amount of a solvency enhancer to the oil system, wherein the solvency enhancer includes Guerbet alcohols. Also provided are methods for preventing sludge and varnish formation in in-service oils including adding an effective amount of a solvency enhancer to the oils, wherein the solvency enhancer includes Guerbet alcohols.

There is disclosed an antifoam component for a mechanical device which includes a fluorinated poly(acrylate) copolymer. The antifoam component has improved foam performance and thermal stability in finished fluids, such as driveline fluids.

Lubricant compositions comprising a base oil, one or more antioxidants selected from a group consisting of N--naphthyl-N-phenylamine antioxidants and diphenylamine antioxidants; and one or more sulfur-containing additives exhibit outstanding oxidative stability and non-corrosion properties. The N--naphthyl-N-phenylamine antioxidants plus diphenylamine antioxidants in total may be present from about 0.2 wt % to about 0.8 wt %, based on the total weight of the lubricant composition. The sulfur provided by the sulfur-containing additives, in total, may be present from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.