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).

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##

Described herein is a process, comprising: a) selecting an API Group II base stock with selected viscosity index and pour point; b) blending a base oil with the base stock, and c) adding to the base oil: i) a liquid ethylene propylene copolymer viscosity modifier that reduces a traction coefficient, and ii) an additive package, to make a driveline fluid that has a defined viscosity index and excellent shear stability. Also provided is a driveline fluid composition having the high viscosity index and excellent shear stability, comprising: a) a base oil comprising from 50 wt % to 100 wt % API Group II base stock; b) a liquid ethylene propylene copolymer viscosity modifier that reduces a traction coefficient; and c) an additive package. Further provided is a method for lubricating an axle or manual transmission by supplying the driveline fluid composition.

The invention relates to a poly alkyl(meth)acrylate polymer comprising a combination of polybutadiene-based monomers having different average molecular weight, lubricant compositions comprising the polymer, a method for manufacturing the polymer and the use of the polymer as a viscosity index improver in a lubricating oil composition.

The invention relates to a poly alkyl(meth)acrylate polymer comprising a combination of polybutadiene-based monomers having different average molecular weight, lubricant compositions comprising the polymer, a method for manufacturing the polymer and the use of the polymer as a viscosity index improver in a lubricating oil composition.

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.

Provided is a lubricating oil composition having excellent detergency and LSPI preventing performance, and specifically a lubricating oil composition including a base oil, a calcium detergent, and a magnesium detergent and/or a sodium detergent, wherein the content of the calcium detergent as converted into a calcium atom and a mass ratio of a magnesium atom (Mg) contained in the magnesium detergent and/or a sodium atom (Na) contained in the sodium detergent to a calcium atom (Ca) [(Mg and/or Na)/Ca] fall within the specific ranges.

A lubricating composition comprises a major amount of an oil of lubricating viscosity and 0.01 to 25 percent by weight based on the weight of the composition, of a poly(2-oxazoline) polymer. The polymer has the repeat unit:

N(COR.sup.1)CH.sub.2CH.sub.2

wherein the number of repeat units (n) in the polymer is an integer between 4 and 1000, such as between 4 and 500. The polymer carries an inorganic or organic nucleophilic polymerisation terminating group (t), and an initiator group (i) connected to the N atom of a repeat unit, the initiator group (i) being effective to initiate the polymerisation of linear, branched or cyclic hydrocarbyl moieties. At least 5% of the total number of the groups R.sup.1 in the polymer comprise alkenyl groups having between 15 and 20 carbon atoms.

The present disclosure also relates to lubrication compositions comprising a long branched ethylene copolymer and methods for making compositions. Compositions of the present disclosure can be a composition including an oil and a ethylene copolymer, the copolymer having one or more of an MWD from about 2.0 to about 6.5; an Mw(LS) from about 30,000 to about 300,000 g/mol; a g.sub.vis of from about 0.5 to about 0.97; an ethylene content of about 40 wt % to less than 80 wt %. The compostion has a shear stability index (30 cycles) of from about 1% to about 60%; and a kinematic viscosity at 100? C. of from about 3 cSt to about 25 cSt. A method of making a composition includes blending an oil with a copolymer is also disclosed. Additionally, provided are novel long chain branched ethylene propylene copolymers and methods to produce such copolymers.

An engine oil composition including greater than 50 wt. % of a base oil of lubricating viscosity selected from a Group III, a Group IV or a Group V base oil, and mixtures thereof, 0.1-10 wt. % of a dispersant viscosity index improver that a reaction product of an olefin copolymer, an acylating agent and a polyamine, one or more calcium-containing detergents that provide from about 900 ppmw to about 2500 ppmw of calcium to the engine oil composition, and one or more molybdenum-containing compounds. The engine oil composition has an SAE viscosity grade of 0W-X or 5W-X, wherein X=16, 20, 30, or 40; from about 500 ppmw to about 1000 ppmw of phosphorus; and a total sulfated ash content of no greater than 1.2 wt. %, as measured by ASTM D874. Methods of using the engine oil composition to lubricate or operate an engine are also described.