A lubricant composition that comprises a hydrocarbon base oil, a polar viscosity improver; and an esterified polyalkylene glycol: R.sup.1[O(R.sup.2O).sub.n(R.sup.3O).sub.m(C═O)R.sup.4].sub.p, wherein R.sup.1 is a linear alkyl having 1 to 18 carbon atoms, a branched alkyl having 4 to 18 carbon atoms or an aryl with 6 to 30 carbon atoms; R.sup.2O is an oxypropylene moiety derived from 1, 2-propylene oxide; R.sup.3O is an oxybutylene moiety derived from butylene oxide, wherein R.sup.2O and R.sup.3O are in a block or a random distribution; R.sup.4 is a linear alkyl with 1 to 18 carbon atoms, a branched alkyl with 4 to 18 carbon atoms or an aryl with 6 to 18 carbon atoms; n and m are each independently integers ranging from 0 to 20 wherein n+m is greater than 0, and p is an integer from 1 to 4. The lubricant composition may have a viscosity index of at least 150, a kinematic viscosity at 100° C. from 2 to 5 centistokes and a kinematic viscosity at −20° C. of at most 600 centistokes.

A polymer surfactant for improving engine oil emulsion properties of a lubricating composition mixed with water and/or fuel contamination, particularly at very cold temperatures, is described herein. In approaches, selected polymeric and functionalized compounds can impart both robust emulsion properties and simultaneously deliver good low temperature fluidity for lubricating compositions that may contain residual amounts of water and/or fuel contamination. Lubricating compositions including such surfactants demonstrate robust properties at temperatures down to about −30° C.

Disclosed is a lubricant composition including: at least one base oil; at least one polyalkylene glycol with at least 50% by weight of butylene oxide units and having a kinematic viscosity, measured at 100° C. according to standard ASTM D445 (2015), which is greater than or equal to 50 mm2/s, a kinematic viscosity, measured at 40° C. according to standard ASTM D445 (2015), which is greater than or equal to 1000 mm2/s and a Viscosity Index, measured according to standard ASTM D2270 (2012), which is greater than or equal to 180. Also disclosed is the use of such a composition for transmission or gear lubrication.

Disclosed is a lubricant composition including: at least one base oil; at least one polyalkylene glycol with at least 50% by weight of butylene oxide units and having a kinematic viscosity, measured at 100° C. according to standard ASTM D445 (2015), which is greater than or equal to 50 mm2/s, a kinematic viscosity, measured at 40° C. according to standard ASTM D445 (2015), which is greater than or equal to 1000 mm2/s and a Viscosity Index, measured according to standard ASTM D2270 (2012), which is greater than or equal to 180. Also disclosed is the use of such a composition for transmission or gear lubrication.

A refrigerating oil comprising a lubricating base oil, a first extreme pressure agent containing sulfur and phosphorus as constituent elements and a second extreme pressure agent containing phosphorus but not containing sulfur as constituent elements, and having a kinematic viscosity at 100° C. of 0.5 mm.sup.2/s or more and 2.5 mm.sup.2/s or less.

A refrigerating oil comprising a lubricating base oil, a first extreme pressure agent containing sulfur and phosphorus as constituent elements and a second extreme pressure agent containing phosphorus but not containing sulfur as constituent elements, and having a kinematic viscosity at 100° C. of 0.5 mm.sup.2/s or more and 2.5 mm.sup.2/s or less.

A lubricating composition comprising a base oil and one or more additives, wherein the composition has: a sulphated ash content (according to ASTM D 874) of at least 0.4 wt % and at most 1.0 wt. %, by weight of the lubricating composition; a total base number (TBN) value (according to ASTM D 2896) of at least 4.0 mg KOH/g and at most 12 mg KOH/g; a total aromatics content contributed by the base oil in the range from 1 wt % to 30 wt %, by weight of the lubricating composition; and a sulphur content contributed by the base oil of 0.4 wt % or less, by weight of the lubricating composition; and wherein the base oil comprises a blend of (i) a first base oil which is a mineral base oil selected from an API Group I mineral base oil and an API Group II mineral base oil, and mixtures thereof, and (ii) a second base oil selected from an API Group II base oil and an API Group III base oil, preferably wherein the first base oil belongs to a different API group to that of the second base oil.

Lubricant compositions comprising a base oil, one or more antioxidants selected from a group consisting of N-α-naphthyl-N-phenylamine antioxidants and diphenylamine antioxidants; and a sulfur-containing additive comprising up to seven carbon atoms exhibit outstanding oxidative stability and non-corrosion properties. The N-α-naphthyl-N-phenylamine antioxidants plus diphenylamine antioxidants in total may be present from about 0.2 wt % to about 0.8 wt %, based on the total weight of the lubricant composition. The sulfur provided by the sulfur-containing additive may be present from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.

Lubricant compositions comprising a base oil, one or more antioxidants selected from a group consisting of N-α-naphthyl-N-phenylamine antioxidants and diphenylamine antioxidants; and a sulfur-containing additive comprising up to seven carbon atoms exhibit outstanding oxidative stability and non-corrosion properties. The N-α-naphthyl-N-phenylamine antioxidants plus diphenylamine antioxidants in total may be present from about 0.2 wt % to about 0.8 wt %, based on the total weight of the lubricant composition. The sulfur provided by the sulfur-containing additive may be present from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.

A lubricant composition for a resin-resin sliding portion or a resin-metal sliding portion that contains a base oil containing a perfluoropolyether oil including a side chain, and a polytetrafluoroethylene having a primary particle diameter of 1 μm or larger and a melamine cyanurate as thickeners.