Lubricant compositions comprising a base oil, one or more antioxidants selected from a group consisting of N--naphthyl-N-phenylamine antioxidants and diphenylamine antioxidants; and one or more sulfur-containing additives exhibit outstanding oxidative stability and non-corrosion properties. The N--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 additives, in total, may be present from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.

A metal detergent and a preparation method thereof and a lubricant oil containing the metal detergent. The metal detergent is sulfurized calcium alkyl phenolate, the method for preparing the metal detergent includes the following steps: a) mixing alkyl phenol, a calcium source and base oil to obtain a mixed solution; b) mixing the mixed solution, ethylene glycol and a sulfur source to carry out sulfurization reaction to obtain a sulfurization reaction solution; c) implementing carbonation reaction between the sulfurization reaction solution and CO.sub.2 to obtain a carbonation reaction solution; and d) extracting the carbonation reaction solution with a solvent, upon refining, to obtain sulfurized calcium alkyl phenolate; wherein the solvent includes solvent oil, water and oxygenous derivative of hydrocarbon. Experimental results show that the content of free alkyl phenol is below 1.5 wt % in the sulfurized calcium alkyl phenolate prepared using the preparation method provided by the present application.

A lubricant composition comprising (a) an oil of lubricating viscosity; (b) at least two nitrogen-containing materials, comprising (i) at least one amide of the formula R.sup.3C(O)NR.sup.1R.sup.2 and (ii) at least one tertiary amine being represented by the formula R.sup.4R.sup.5NR.sup.6 where R.sup.4 and R.sup.5 are alkyl groups of at least 6 carbon atoms and R.sup.6 is a polyhydroxyl-containing alkyl group or a polyhydroxyl-containing alkoxyalkyl group; (c) a functionalized dispersant component, and (d) at least one diallyl phosphite, provides good lubricant performance for a continuously variable transmission.

A lubricant composition comprising (a) an oil of lubricating viscosity; (b) at least two nitrogen-containing materials, comprising (i) at least one amide of the formula R.sup.3C(O)NR.sup.1R.sup.2 and (ii) at least one tertiary amine being represented by the formula R.sup.4R.sup.5NR.sup.6 where R.sup.4 and R.sup.5 are alkyl groups of at least 6 carbon atoms and R.sup.6 is a polyhydroxyl-containing alkyl group or a polyhydroxyl-containing alkoxyalkyl group; (c) a functionalized dispersant component, and (d) at least one diallyl phosphite, provides good lubricant performance for a continuously variable transmission.

A sulphurised calcium phenate detergent is made by (i) reacting hydrogenated distlled CNSL with a calcium salt and sulphur in the presence of a promoter and process solvent; (ii) reacting the product of (i) with additional calcium salt and promoter, and with a co-surfactant, and then carbonating; and optionally (iii) further carbonating the reaction mixture to obtain overbased sulphurised calcium phenate.

The disclosed technology relates to a lubricant composition for automotive or industrial gears, as well as axles and bearings, the automotive or industrial gear oil containing an oil of lubricating viscosity, an optional phosphate and/or thiophosphate compound, a particular sulfurized olefin, either a metal thiophosphate compound, such as zinc dialkyldithiophosphate, a thiadiazole functionalized dispersant, or a mixture thereof, and a hydroxyl/amine containing booster, as well as a method of improving automotive or industrial gear operating efficiency and temperature by lubricating such automotive or industrial gears with the automotive or industrial gear oil.