The present invention provides a viscosity index improver having an excellent viscosity index improving effect, a lubricant composition having excellent low-temperature viscosity in which the viscosity reduction due to long-term use is small, and a method for producing the lubricant composition. A viscosity index improver of the present invention contains a copolymer (A) containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number (Q) of 29 or more, and the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer (A).

Disclosed are Group III base stocks comprising greater than or equal to about 90 wt. % saturated hydrocarbons (saturates); a viscosity index from 120 to 145; a unique ratio of molecules with multi-ring naphthenes to single ring naphthenes (2R+N/1RN); a unique ratio of branched carbons to straight chain carbons (BC/SC); a unique ratio of branched carbons to terminal carbons (BC/TC); and unique MRV behavior as a function of base stock naphthene ratio (2R+N/1RN). A method for preparing the base stocks is also disclosed. Also disclosed is a lubricating oil having the base stock as a major component, and an additive as a minor component.

The invention has an object of providing ethylene/-olefin copolymers having high randomness and a small number of double bonds in the copolymers. The ethylene/-olefin copolymers of the invention are obtained by copolymerizing ethylene and an -olefin having 3 to 20 carbon atoms in the presence of an olefin polymerization catalyst which includes a bridged metallocene compound (A) represented by the formula [I], and at least one compound (B) selected from organometallic compounds (B-1), organoaluminum oxy compounds (B-2) and compounds (B-3) capable of reacting with the bridged metallocene compound (A) to form an ion pair, and have a specific weight average molecular weight, a specific molecular weight distribution, a specific glass transition point and a specific value B. ##STR00001##

Provided is a lubricating oil composition comprising a base oil (A) containing a polyalkylene glycol (A1) and a polyol ester (A2), a phosphorus-based rust inhibitor (B), and an antioxidant (C) containing an amine-based antioxidant (C1). The lubricating oil composition exhibits a strong effect for suppressing sludge sedimentation even when used for an extended period of time in a high-temperature environment, and has excellent demulsibility and rust preventive properties, and therefore, can be suitably used in turbomachinery, compressors, hydraulic equipment, and machine tools.

Lubricating oil compositions are provided which contain bimodal copolymer compositions, and in particular bimodal ethylene--olefin copolymer compositions. The copolymer compositions comprise first and second ethylene--olefin copolymer components. The bimodal compositions are particularly useful as viscosity or rheology modifiers, e.g., in lubricating oil compositions. Lubricating oil compositions comprising the copolymer compositions advantageously exhibit enhanced shear stability index (SSI) and thickening efficiency (TE) values, while maintaining excellent low-temperature properties such as pour point, mini-rotary viscometer viscosity, and cold crank simulation performance.

A fuel composition including a fuel and a fuel additive including a fuel soluble detergent selected from succinimide compounds of the Formula (I), Mannich detergents of the formulae (IIa), and amine detergents of the formulae (IIIa) and (IIIb). The fuel soluble detergents are derived from a specific class of ethylene-alpha olefin copolymers having an Mn of less than 5,000 g/mol, an ethylene unit content of more than 40 mol % to less than 90 mol %; a terminal unsaturation of 70 mol % or greater; at least 70 mol % of the unsaturation is terminal vinylidene, one or more tri-substituted isomers of the terminal vinylidene or any combination thereof, an average ethylene run length of less than 2.6; and wherein n.sub.C2,Actual>n.sub.C2,Statistical. Methods employing the fuel compositions for operating diesel and gasoline engines to reduce injector valve deposits, valve sticking and injector nozzle fouling, and a method for stabilizing a diesel fuel composition.

Lubricating oil compositions including olefin copolymer dispersants comprising olefin copolymers derived from ethylene and one or more C.sub.3-C.sub.10 alpha olefins in combination with various additives and related methods are generally described herein. The compositions may include one or more phosphorus-containing compound(s), detergents, friction modifiers, extreme pressure agents, and mixtures thereof.

A novel hydraulic fluid composition for application to drilling equipment is described herein. These hydraulic fluid compositions permit effective monitoring or controlling well-head pressure of a well during drilling on land or offshore. The hydraulic fluid compositions prevent uncontrolled flow of gas, oil, or another well fluid out of an underground formation during a drilling or extraction process when applied to the drilling equipment. Accordingly, provided is a hydraulic fluid concentrate which contains a water-soluble phosphate ester and a sulfide compound containing at least one SS linkage, at least 10 carbon atoms and at least one terminal carboxylate group, wherein the SS linkage bridges two alkyl groups. Additional components can be added to the concentrate and include one or more alkaline compound, one or more dicarboxylic acid or salt thereof, a water-soluble corrosion inhibitor, a water-soluble biocide, a pour point depressant, and water, ethylene glycol, or a combination thereof. The concentrate is then further diluted by the customer for use as described herein. Particularly, these compositions are effective in reducing seawater corrosion of a metal in contact with the hydraulic fluid composition, reducing bioaccumulation in oil drilling equipment contacted with the hydraulic fluid composition, and have low toxicity to sea life.

The present invention relates to a functional fluid composition comprising a glycol as a base material and a diamine-based noise reducer. According to the present invention as such, the functional fluid composition comprising a glycol as a base material and a diamine-based noise reducer represented by chemical formula 1 has an excellent noise reducing effect. In addition, the functional fluid composition of the present invention has an excellent metal corrosion inhibiting effect even, by using a diamine-based compound as a noise reducer, when a metal corrosion inhibitor composed of a triazole-based compound without including an amine-based compound is used as a metal corrosion inhibitor.

The present invention relates to a functional fluid composition comprising a glycol as a base material and a monoamine-based noise reducer. According to the present invention as such, the functional fluid composition comprising a glycol as a base material and a monoamine-based noise reducer represented by chemical formula 1 has an excellent noise reducing effect. In addition, the functional fluid composition of the present invention has an excellent metal corrosion inhibiting effect even, by using a monoamine-based compound as a noise reducer, when a metal corrosion inhibitor composed of a triazole-based compound without including an amine-based compound is used as a metal corrosion inhibitor.