Disclosed are lubricant compositions with improved oxidation stability which are prepared with 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 (BC/SC) carbons; and a unique ratio of branched carbons to terminal chain (BC/TC) carbons.

Disclosed are Group III base stocks comprising at least 30 wt % naphthenes, a viscosity index from 120 to 145; and a unique ratio of molecules with multi-ring naphthenes to single ring naphthenes (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.

Disclosed are lubricant compositions prepared with 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); and a unique ratio of branched carbons to straight chain (BC/SC) carbons; 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).

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.

A lubricating composition comprises a major amount of an oil of lubricating viscosity and 0.01 to 25 percent by mass, based on the mass of the composition of an oil-soluble copolymer, The copolymer comprises units (a) and units (b):

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

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

wherein 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 (a) or (b), the initiator group (i) being effective to initiate the polymerisation of linear branched or cyclic hydrocarbyl moieties. R.sup.1 and R.sup.2 are the same or different and comprise a single or a mixture of linear, branched or cyclic hydrocarbyl groups having 1-50 carbon atoms, some or all having 12-50 carbon atoms, or of at least one macro-monomeric hydrocarbyl group with more than 50 carbon atoms.

The present invention relates to a lubricant composition suitable for use in an electric vehicle. The lubricant composition comprises a traction coefficient additive and wherein the traction coefficient additive is an ester, said ester being the reaction product of at least one saturated branched-chain aliphatic monohydric alcohol having between 12 and 32 carbon atoms and at least one aliphatic carboxylic acid having between 6 and 32 carbon atoms. The lubricant composition as described herein provides an electric vehicle gear oil and imparts desirable coefficient of traction properties when in use.

A lubricating oil composition, containing a base oil (A) that satisfies the following requirements (A-1) to (A-4), and a polymer (B) that satisfies the following requirements (B-1) and (B-2): (A-1): a 100? C. kinematic viscosity is 2.0 mm.sup.2/s or more and less than 7.0 mm.sup.2/s, (A-2): a viscosity index is 100 or more, (A-3): a content of cycloparaffin is 35.0% by volume or less based on a total volume of the base oil (A), (A-4): an aromatic content (% CA) is less than 1.0, (B-1): a ratio of a mass-average molecular weight (Mw) to a number-average molecular weight (Mn), [Mw/Mn] is 1.0 or more and less than 6.0, (B-2): a ratio of a peak integral value (I.sub.10) at a chemical shift 10.0 to 11.0 ppm to a peak integral value (I.sub.14) at a chemical shift 13.5 to 14.5 ppm, as determined in .sup.13C-NMR analysis, [I.sub.10/I.sub.14] is 0.05 or more.

The present invention relates to a base oil. The base oil as described herein provides utility inter alia in gear oil formulations, and in particular transmission fluids, and provides improved coefficient of friction properties when in use. More especially in some embodiments there is provided a gear oil formulation which is particularly suitable for use in electrical vehicles with or without integrated gear boxes.

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.