A lubricating oil composition which contains, or is made by admixing: (A) an oil of lubricating viscosity, in a major amount; (B) at least one oil-soluble or oil-dispersible sulfurized fatty acid ester, as an additive in an amount providing the lubricating oil composition with greater than or equal to 0.02 mass % sulphur; and, (C) at least one oil-soluble or oil-dispersible alkali metal or alkaline earth metal salicylate detergent, as an additive in an effective minor amount, providing greater than or equal to 5 mmol of salicylate soap per kilogram of the lubricating oil composition,
wherein the lubricating oil composition does not contain a phosphorus ester additive.

Disclosed is a lubricating oil composition containing a base oil, a viscosity index improver, a molybdenum-based friction modifier, a boron-containing dispersant, and at least two extreme-pressure additives selected from a sulfur-based extreme-pressure additive, a phosphorous-based extreme-pressure additive and a sulfur/phosphorus-based extreme-pressure additive, or a sulfur/phosphorus-based extreme-pressure additive. The base oil is a synthetic oil having a kinematic viscosity at 100° C. of 3 mm.sup.2/s or more and 10 mm.sup.2/s or less, the viscosity index improver is a resin having a number average molecular weight (Mn) of 1,000 or more and 10,000 or less, the mass ratio of boron atoms (B) contained in the boron-containing dispersant to molybdenum atoms (Mo) contained in the molybdenum-based friction modifier, [(B)/(Mo)] is 1 or more and 5 or less, and the mass ratio of sulfur atoms (S) to phosphorus atoms (P) contained in the extreme-pressure additive(s), [(S)/(P)] is 10 or more and 20 or less.

The present invention provides a lubricating oil composition not containing ZnDTP but comprising: (a) a base oil; (b) molybdenum dialkyldithiocarbamate; and (c) an organic acid metal salt compound having a metal of Group 8 of a short periodic table, copper, or bismuth as a central metal.

Lubricating compositions for motor vehicles are disclosed. The lubricating composition is of grade according to the SAE J300 classification defined by the formula (X)W(Y), wherein X represents 0 or 5; and Y represents an integer ranging from 4 to 20; and comprises at least one diester of formula R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O).sub.s—C(O)—R.sup.b (I). The composition may be used as a lubricant for an engine, in particular a vehicle engine, to reduce the fuel consumption of the engine and to improve engine cleanliness

A lubricant composition includes: an oil selected from among polyalkylene glycols (PAG); and a nitrogen compound selected from among amine phosphates or amine tungstates. The lubricant composition is particularly suitable for lubricating a vehicle engine, preferably a motor vehicle engine. Also disclosed is an engine lubrication method utilizing such composition.

A lubricating oil composition which can reduce the occurrence frequency of LSPI and which can ensure detergency. The lubricating oil composition which includes a lubricant base oil, a compound having calcium and/or magnesium, a compound having molybdenum and/or phosphorus, and an ashless dispersant having nitrogen and which satisfies X0.85 and Y0.18 (wherein X is calculated according to formula (1): X=([Ca]+0.5[Mg])8[Mo]8[P]30 and Y is calculated according to formula (2): Y=[Ca]+1.65[Mg]+[N]). The lubricating oil composition for use in an internal combustion engine, more particularly, a lubricating oil composition for use in a supercharged gasoline engine.

A lubricant composition including a binuclear molybdenum compound (A) and a trinuclear molybdenum compound (B), wherein these compounds are included in a range represented by (molybdenum of the binuclear molybdenum compound (A)):(molybdenum of the trinuclear molybdenum compound (B))=99.98:0.02 to 95:5 as a mass ratio.

To provide a friction-reducing agent containing no sulfur nor phosphorus and being excellent in friction-reducing properties, and a lubricating oil composition using it. An alkanolamine represented by the following formula is used as a friction-reducing agent: ##STR00001##
wherein A.sub.1 and A.sub.2 are each independently a hydroxy group or a hydrogen atom, provided that A.sub.1 and A.sub.2 are not hydrogen atoms at the same time, R.sub.1 is a hydrocarbon group having at most 30 carbon atoms, R.sub.2 to R.sub.6 are each independently a hydrogen atom or a hydrocarbon group having at most 30 carbon atoms, and m and n are each independently an integer of from 0 to 10.

The present invention is directed to a use of a lubricant in a diesel engine to disperse soot produced by the diesel engine, the soot being dispersed without adversely affecting the viscosity of the lubricant; the lubricant comprising a major amount of oil of lubricating viscosity and a minor amount of a dispersant comprising (i) one or more olefin, (ii) one or more carboxylic acid, (iii) one or more polyetheramines and (iv) one or more aromatic amines along with co-additives.

A sliding member has a sliding surface sliding under a wet condition in which a lubricant oil exists. The sliding surface is coated with a laminate film comprising an upper layer and a lower layer. The lower layer comprises hydrogen-free amorphous carbon (hydrogen-free DLC) and carbon particles dispersed on or in the hydrogen-free DLC. The hydrogen-free DLC has a hydrogen content of 5 atom % or less when the lower layer as a whole is 100 atom %. The upper layer comprises boron-containing amorphous carbon (B-DLC) and has protrusions on a surface side of the upper layer along the carbon particles of the lower layer. The B-DLC has a boron content of 1-40 atom % when the upper layer as a whole is 100 atom %. The protrusions have a particle diameter of 0.5-5 m and exist with a density of 20 protrusions/100 m.sup.2 or more.