A lubricating oil composition including: a lubricating base oil; (A) a poly(meth)acrylate having a weight average molecular weight of no more than 50,000, in an amount of 2 to 10 mass %; (B) a phosphite ester of the general formula (1) in an amount of 0.01 to 0.06 mass % in terms of P; (C) a thiadiazole compound in an amount of 0.01 to 0.2 mass %; and (D) a Ca salicylate detergent in an amount of 0.005 to 0.03 mass % in terms of Ca, wherein the lubricating oil composition has a kinematic viscosity at 40° C. of 4.0 to 20.0 mm.sup.2/s, and a kinematic viscosity at 100° C. of 1.8 to 5.2 mm.sup.2/s; and has a ratio [S]/[P] of 2.2 to 4.0, wherein the [S] represents a sulfur content, and the [P] represents a phosphorus content: ##STR00001##
wherein R.sup.1 and R.sup.2 are each independently a group having 5 to 20 carbons represented by the general formula (2); and ##STR00002##
wherein R.sup.3 is a C2-17 linear chain hydrocarbon group, and R.sup.4 is a C2-17 linear chain hydrocarbon group.

The disclosed technology provides a lubricating composition and a method of lubricating an internal combustion engine where the lubricating composition contains an oil of lubricating viscosity, one or more metal-containing, sulfur-free, alkyl-phenol based detergents, an alkaline earth metal sulfonate detergent, a polyisobutenyl succinimide dispersant, and a dispersant viscosity modifier having a number average molecular weight of at least 20,000. The lubricating composition of the present invention can be formulated to have lower HTHS viscosity, and reduced phosphorous content, while providing protection against adhesive wear.

A lubricating oil composition is provided which comprises (a) greater than 50 wt. % of a base oil of lubricating viscosity; and (b) 0.1 to 20 wt. % of an alkyl-substituted hydroxyaromatic carboxylic acid, wherein the alkyl substituent of the alkyl-substituted hydroxyaromatic carboxylic acid has from 12 to 40 carbon atoms; wherein the lubricating oil composition is a monograde lubricating oil composition meeting specifications for SAE J300 revised January 2015 requirements for a SAE 20, 30, 40, 50, or 60 monograde engine oil, and has a TBN of 5 to 200 mg KOH/g, as determined by ASTM D2896.

A lubricating oil composition including: a lubricant base oil; (A) a triazole metal deactivator in an amount of 0.005 to 0.03 mass % in terms of nitrogen on the basis of the total mass of the composition; and (B1) a succinimide compound represented by the following general formula (1) in an amount of 0.0005 to 0.02 mass % in terms of nitrogen on the basis of the total mass of the composition: ##STR00001##
wherein in the general formula (1), R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a C1-36 linear or branched chain alkyl or alkenyl group, and at least one of R.sup.1 and R.sup.2 is a C8-36 linear or branched chain alkyl or alkenyl group, and n represents an integer of 1 to 10.

To provide a composition for a heat cycle system, which comprises a working fluid for heat cycle which has a low global warming potential and high stability, and which can replace R410A, and a heat cycle system employing the composition. A composition for a heat cycle system, which comprises a working fluid for heat cycle containing trifluoroethylene, and a stabilizer for preventing deterioration of the working fluid for heat cycle, such as an oxidation resistance-improving agent, a heat resistance-improving agent or a metal deactivator, and a heat cycle system employing the composition for a heat cycle system.

The present invention relates to a lubricant composition containing: a base oil (A); at least one kind of calcium-based detergent (B) selected from (B1) calcium sulfonate having a base number of 5.00 mgKOH/g or more and 100 mgKOH/g or less, (B2) calcium salicylate having a branched acyclic hydrocarbon group, and (B3) overbased calcium phenate having a branched acyclic hydrocarbon group; and at least one kind of ashless detergent (C) selected from (C1) a hindered amine compound having one piperidine-derived backbone in a molecule, and (C2) a specific diethanolamine compound. In the lubricant composition, the calcium atom content is 100 ppm by mass or more and 600 ppm by mass or less with respect to the total mass of the lubricant composition, and the ratio (N.sub.C/Ca.sub.B) of the nitrogen atom content (N.sub.C) of the ashless detergent (C) to the calcium atom content (Ca.sub.B) of the calcium-based detergent (B) is 1.3 to 3.1 as a mass ratio.

The present invention relates to a lubricant composition containing: a base oil (A); at least one kind of calcium-based detergent (B) selected from (B1) calcium sulfonate having a base number of 5.00 mgKOH/g or more and 100 mgKOH/g or less, (B2) calcium salicylate having a branched acyclic hydrocarbon group, and (B3) overbased calcium phenate having a branched acyclic hydrocarbon group; and at least one kind of ashless detergent (C) selected from (C1) a hindered amine compound having one piperidine-derived backbone in a molecule, and (C2) a specific diethanolamine compound. In the lubricant composition, the calcium atom content is 100 ppm by mass or more and 600 ppm by mass or less with respect to the total mass of the lubricant composition, and the ratio (N.sub.C/Ca.sub.B) of the nitrogen atom content (N.sub.C) of the ashless detergent (C) to the calcium atom content (Ca.sub.B) of the calcium-based detergent (B) is 1.3 to 3.1 as a mass ratio.

A crankcase lubricating oil composition for the crankcase of a spark-ignited or compression-ignited internal combustion engine, comprising a magnesium-containing detergent, in an amount sufficient to provide from 200-4000 ppm magnesium to the lubricating oil composition, in combination with an oil-soluble or oil-dispersible molybdenum compound in an amount sufficient to provide from 600-1500 ppm molybdenum atoms to the lubricating oil composition, and with an oil-soluble or oil-dispersible boron-containing compound in an amount sufficient to provide from 200-600 ppm boron atoms to the lubricating oil composition to improve the friction and fuel economy performance.

A crankcase lubricating oil composition for the crankcase of a spark-ignited or compression-ignited internal combustion engine, comprising a magnesium-containing detergent, in an amount sufficient to provide from 200-4000 ppm magnesium to the lubricating oil composition, in combination with an oil-soluble or oil-dispersible molybdenum compound in an amount sufficient to provide from 600-1500 ppm molybdenum atoms to the lubricating oil composition, and with an oil-soluble or oil-dispersible boron-containing compound in an amount sufficient to provide from 200-600 ppm boron atoms to the lubricating oil composition to improve the friction and fuel economy performance.

The use of polyalkylenyl succinic anhydrides to stabilise an additive concentrate which includes a salicylate detergent and a nitrogen-free ashless organic friction modifier.