A comb polymer can be used for reducing a Noack evaporation loss of a lubricant composition, especially of an engine oil composition. Application of the comb polymer to the lubricant composition can bring about the desired reduction. The comb polymer can include specified amounts of macromonomer and alkyl acrylates. Resulting lubricant compositions can include the comb polymer.

The invention provides a lubricating composition comprising an oil of lubricating viscosity and synergistic mixture of a functionalized ethylene--olefin copolymer, a poly(meth)acrylate block polymer having a substantially oil soluble block and a substantially oil insoluble block. The invention also provides a method of lubricating a mechanical device using such a lubricating composition.

The purpose of the present invention is to provide organometallic salt compositions that are useful as lubricant additives and/or in lubricant additive compositions to reduce friction and wear, and also have improved solubility in all four types of hydrocarbon base oils (Groups I-IV) at a variety of concentrations and under a variety of conditions. The organometallic salt composition is derived from at least one long chain monocarboxylic acid and a single metal in combination with at least one short or medium branched-chain monocarboxylic acid. The compositions are particularly useful in combination with activated complexes comprising a first metal component, a second metal component and particles comprising the first metal component.

A lubricant composition comprising a high-viscosity PAO lubricant base stock having a KV100 of at least 200 cSt and comprising multiple PAO molecules comprising at least 200 carbon atoms per molecule, wherein (i) each of the PAO molecules comprises multiple pendant groups; (i) the average pendant group length of all the pendant groups excluding one methyl on each of the PAO molecules among at least 90 mol % of all of the PAO molecules, if one or more methyl is present, is at least 6.0, and (iii) the concentration of the high-viscosity PAO base stock is no more than 75 wt % of the total weight of the lubricant composition. The lubricant composition exhibits provides a high degree of protection of gear surfaces as measured by ASTM D5182.

This lubricant base oil includes a condensation ester of an alcohol (A) and a carboxylic acid (B), wherein the alcohol (A) contains a polyhydric alcohol represented by general formula (1) (in formula (1), R.sup.1-R.sup.4 independently represent a hydrogen atom, a methyl group, or a hydroxyl group, and at least two of R.sup.1-R.sup.4 each represents a hydroxyl group), and the carboxylic acid (B) contains a C4-C8 cycloalkane monocarboxylic acid. The lubricant base oil has excellent heat resistance and lubricating property.

A viscosity index improver containing a copolymer (A) whose essential constituent monomer is a monomer (a) having a number average molecular weight of 800 to 4,000 represented by the following formula (1), the copolymer (A) having a solubility parameter in the range of 9.00 to 9.40:

##STR00001##

wherein R.sup.1 is a hydrogen atom or a methyl group; X.sup.1 is a group represented by O, O(AO).sub.m, or NH, AO is a C2-C4 alkyleneoxy group, m is an integer of 1 to 10, each AO may be the same or different when m is 2 or more, and the (AO).sub.m moieties may be randomly bonded or block-bonded; R.sup.2 is a residue after removal of one hydrogen atom from a hydrocarbon polymer whose essential constituent monomer is butadiene in which the butadiene is present in a proportion of 50% by weight or more based on the weight of R.sup.2, or after removal of one hydrogen atom from a polymer formed by partial hydrogenation of the hydrocarbon polymer; and p represents a number of 0 or 1.

A fluid contains a base oil consisting of an alcohol-initiated polyalkylene glycol where polyalkylene glycol component is selected from a homopolymer of 1,2-butylene oxide and copolymer of 1,2-butylene oxide and propylene oxide; a glycerol-initiated unsaturated ester that is free of tertiary carbon atoms and quaternary carbon atoms; and an antioxidant.

A fluid contains a base oil consisting of an alcohol-initiated polyalkylene glycol where polyalkylene glycol component is selected from a homopolymer of 1,2-butylene oxide and copolymer of 1,2-butylene oxide and propylene oxide; a glycerol-initiated unsaturated ester that is free of tertiary carbon atoms and quaternary carbon atoms; and an antioxidant.

A conductive lubricating oil composition including at least one lubricating base oil selected from the group consisting of compounds represented by the following General Formula (1) and compounds represented by the following General Formula (2), and at least one conductivity imparting agent selected from the group consisting of potassium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, potassium bis(trifluoromethanesulfonyl)imide, and lithium tris(trifluoromethanesulfonyl)methide, in an amount of from 0.01% by mass to 1% by mass, and having a rate of change in conductivity after storage at 120 C. for 200 hours of 10% or less. The definitions of R.sup.1, R.sup.2, m and n in the formulae are as indicated in the specification. Cases of mn=2 are excluded. ##STR00001##

The invention is a fluid having a kinematic viscosity from 3 to 6 mm.sup.2/s, a flash point of higher than 120 C. and a pour point lower than 40 C., having a boiling point in the range of from 200 C. to 400 C. and a boiling range below 80 C., said fluid comprising more than 95% isoparaffins and less than 3% of naphthens by weight, a biocarbon content of at least 95% by weight, containing less than 100 ppm aromatics by weight. The invention is also a drilling fluid and the use of the fluid to improve the viscosity of the drilling fluid.