A method of increasing the spreading of a lubricant on the liner surface after it's delivery, wherein the method comprises preparing the lubricant compositions comprising copolymers of monomers (A) selected from C6-C10 alkyl methacrylate monomers, and monomers (B) selected from C10-C18 alkyl methacrylate monomers, and a base oil or comprising a copolymer obtained by combining at least monomers (A) selected from C6-C10 alkyl methacrylate monomers, and monomers (B) selected from C10-C18 alkyl methacrylate monomers in a mixture and co-polymerizing the monomers for increasing the spreading and/or the self-spreading of the lubricant on the cylinder liner surface after its delivery.

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 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.

The present invention relates to a polyether compound having a halogen atom content of 0.1000% by mass or less in terms of a polymer molecule thereof as measured by combustion ion chromatography and a weight average molecular weight (Mw) of 140,000 or more and 1,000,000 or less.

The invention provides a method of lubricating a transmission which includes a synchronizer with a non-metallic surface, the method comprising supplying thereto a lubricant comprising: (a) an oil of lubricating viscosity; (b) an alkaline earth metal detergent; and (c) a non-aromatic carboxylic acid or a salt thereof having 8 to 24 carbon atoms.

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.

The presently claimed invention is directed to poly(meth)acrylate copolymers containing alkyl(meth)acrylate comonomer with branched C17 alkyl group. The invention is further related to lubricating oil compositions comprising poly(meth)acrylate copolymers containing alkyl(meth) acrylate comonomer with branched C17 alkyl group as viscosity index improving component.

The invention refers to use of lubricant compositions comprising a specific diester and additives to reduce the fuel consumption of an engine.

Trunk piston marine engine crackcase lubrication is effected by a composition made by blending minor amounts of (A) a metal dithiophosphoric acid salt additive component comprising 50 mole % or more of a zinc di (C.sub.6 primary alkyl) dithiophosphate, and (B) an overbased metal detergent additive component, with (C) a major amount of an oil of lubricating viscosity.