A turbine oil used in a turbine of a jet engine, containing: a base oil (A) containing a polyol ester (A1); an antioxidant (B) containing an amine-based antioxidant (B1); a polymethacrylate (C) having a weight average molecular weight of 50,000 to 600,000; and an alkyl aromatic compound (D), having a content of the component (D) of 1,000 parts by mass or less per 100 parts by mass of a total resin content of the component (C), and satisfying the following requirements (1) and (2): requirement (1): a viscosity index of 140 or more; and requirement (2): a coking amount attached to a panel of 80 mg or less after a panel coking test under the prescribed condition. The turbine oil has a high viscosity index to such an extent that an oil film can be retained in the use under a high temperature environment as in a turbine of a jet engine mounted on an aircraft, and is excellent in low temperature viscosity characteristics while retaining excellent heat resistance.

A liquid blend of octylated phenyl-α-naphthylamine, and at least one low molecular weight aromatic ester, wherein the octylated phenyl-α-naphthylamine is present from about 15% to about 35% by weight of the blend, as well as a lubricating composition comprising a lubricant base and an amount of the blend which provides up to 2.0% by weight of the octylated phenyl-α-naphthylamine in the composition.

Provided is a lubricating oil composition for use in turbomachinery, compressors, hydraulic equipments, or machine tools, which contains a mineral oil (A) and a synthetic oil (B) containing a polyalkylene glycol (B1) and a polyol ester (B2), in which the content of the mineral oil (A) is 5 to 95% by mass based on the total amount of the lubricating oil composition, and which is used in turbomachinery, compressors, hydraulic equipments, or machine tools. The lubricating oil composition is excellent in oxidation stability, has a strong effect of preventing sludge precipitation and has excellent water separability even in use for a long period of time in high-temperature environments.

The disclosed technology provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, a 300 TBN or higher alkaline earth metal sulfonate detergent having a metal ratio of 10 to 40, an alkaline earth metal sulfonate detergent having a metal ratio of 3 to 9, and a TBN of 81 to 180 mg KOH/g, wherein the sulfonate detergents provide a total amount of sulfonate substrate of 1 wt % to 3 wt % of the lubricating composition, 0.1 to 1.2 wt % of antioxidant, wherein at least 20 wt % of the antioxidant is a phenolic antioxidant, a borated compound present in an amount to deliver 25 ppm to 300 ppm of boron, the lubricating composition has a sulfated ash content of 0.5 wt % to not more than 1.5 wt %, and the lubricating composition has a TBN of 6.5 to 15 mg KOH/g.

A grease composition includes base oil, a thickener, and an inorganic additive. The base oil is a poly--olefin having a base oil kinematic viscosity of 15 to 50 mm.sup.2/s at 40 C. The thickener is a diurea expressed by Structural Formula (1). The content of the thickener is 10 to 22 mass % with respect to the total amount of the base oil and the thickener. The inorganic additive is a mixture containing sepiolite and bentonite, and is organically modified. The content of the inorganic additive is 2 to 20 mass % with respect to the total amount of the base oil and the thickener.
R.sup.1NHCONHR.sup.2NHCONHR.sup.3(1)

Disclosed herein is a process for lubricating an internal combustion engine with a lubricant composition that may be substantially ash free. The ashless lubricant composition described herein may comprise primary antioxidants, such as aminic diphenyl amines, alkylated phenyl-naphthyl amines, and phenolic antioxidants. The ashless lubricant composition described herein may also comprise sulfur containing products that may work as secondary antioxidants. Other components such as ashless antiwear components, dispersants, pour point depressants, friction modifiers, and metal deactivators may also be used to formulate an ashless lubricant composition according to an embodiment.

The lubricating oil composition of the present invention contains a base oil, a 2,6-di-tert-butylphenol (A), and at least one compound (B) selected from a benzotriazole compound and a sorbitan compound.

Provided is a lubricating oil composition containing a mineral base oil (A) having a temperature gradient |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.

The present invention provides a mineral base oil having a kinetic viscosity at 100 C. of 7 mm.sup.2/s or more and less than 10 mm.sup.2/s, a viscosity index of 100 or more, and a temperature gradient |*| complex viscosity between two temperature points of 5 C. and 15 C. of 240 mPa.Math.s/ C. or less as measured with a rotary rheometer at an angular velocity of 6.3 rad/s. The use of the mineral base oil enables easy preparation of a lubricating oil composition and a grease composition having excellent oxidation stability while ensuring the freedom of selection of additives.

Alkylated diaryl amines further substituted by an alkoxy group on one or more aryl carbon atoms exhibit excellent antioxidant activity in lubricant compositions.