The lubricating oil composition for gas engine of the present invention contains (A) a base oil, (B1) an overbased calcium salicylate, (B2) an overbased sodium sulfonate, (C1) an amine-based antioxidant, and (C2) a phenol-based antioxidant, a total content of the amine-based antioxidant (C1) and the phenol-based antioxidant (C2) being 4 mass % or more on a basis of the whole amount of the composition.

The lubricating oil composition for gas engine of the present invention contains (A) a base oil, (B1) an overbased calcium salicylate, (B2) an overbased sodium sulfonate, (C1) an amine-based antioxidant, and (C2) a phenol-based antioxidant, a total content of the amine-based antioxidant (C1) and the phenol-based antioxidant (C2) being 4 mass % or more on a basis of the whole amount of the composition.

A rolling bearing (1) includes an outer ring (2), an inner ring (4), and a plurality of rolling elements (6) arranged between the outer and inner ring (2, 4). The rolling bearing (1) is provided with lubricant. The outer ring (2) has an outer contact width (b.sub.o) between the outer ring (2) and the rolling elements (6). The inner ring (4) has an inner contact width (b.sub.i) between the inner ring (4) and the rolling elements (6). A ratio =b.sub.i/b.sub.o between the inner and outer contact width (b.sub.i, b.sub.o) is larger than 1.65 or a ratio =b.sub.i/b.sub.o between the inner and outer contact width (b.sub.i, b.sub.o) is larger than 0.97 and smaller than 1.06 or a ratio =b.sub.i/b.sub.o between the inner and outer contact width (b.sub.i, b.sub.o) is smaller than 0.68.

A lubricant composition includes an oil including a plurality of long-chain hydrocarbon molecules. A quantity of a catalytically active metal-organic additive is mixed with the oil. The metal-organic additive is formulated to fragment the long-chain hydrocarbon molecules of the oil into at least one of dimers and trimers under the influence of at least one of a mechanical loading and a thermal loading. In some embodiments, the metal-organic additive includes a compound of formula II: ##STR00001##
where: X is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg or Cn, and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are alkyl or alkyl halide.

A lubricating oil composition for an internal combustion engine according to the present invention contains a lubricating base oil, (A1) a basic calcium salicylate having a TBN of 200 mgKOH/g or more, (A2) a basic sodium sulfonate having a TBN of 200 mgKOH/g or more and/or a basic calcium sulfonate having a TBN of 50 mgKOH/g or less, (B) a binuclear organic molybdenum compound and/or a trinuclear organic molybdenum compound, and (C) a polyalkyl (meth)acrylate having an SSI of 30 or less, a total content of molybdenum derived from the binuclear and trinuclear organic molybdenum compounds being 0.025 mass % or more relative to the whole amount of the composition and the lubricating oil composition having predetermined values of a high-temperature high-shear viscosity and a NOACK value (250 C., 1 hr).

A lubricating oil composition is provided. The composition includes major amount of an oil of lubricating viscosity, or more alkaline earth metal detergent, one or more nitrogen-containing dispersant, and up to about 0.10 wt % of zinc from zinc dithiophosphate. The lubricating oil composition has sulfur content of up to 0.10 wt %, sulfated ash content of up to 0.30 wt %, and the ratio of total nitrogen concentration to total alkaline earth metal concentration from the one or more alkaline earth metal detergent is about 20 or greater.

A lubricating oil composition includes: a lubricant base having a kinematic viscosity at 100 C. of 1.0 to 10 mm.sup.2/s and % C.sub.P of no less than 70; (A) 0.1 to 30 mass % of a poly(meth)acrylate viscosity index improver having a PSSI of no more than 5, a weight average molecular weight of 10,000 to 500,000, a ratio A/B of less than 2.4 and a ratio C/B of less than 1.4, the ratio A/B being a ratio of a viscosity increase effect A on kinematic viscosity at 100 C. to a viscosity increase effect B on HTHS viscosity at 150 C., and the ratio C/B being a ratio of a viscosity increase effect C on kinematic viscosity at 150 C. to the viscosity increase effect B on HTHS viscosity at 150 C.; and (B) 0.01 to 2.0 mass % of a friction modifier.

Provided are a lubricating oil composition for internal combustion engine capable of preventing a deterioration of the combustion state of a spark-ignition internal combustion engine, specifically, a lubricating oil composition to be used for a spark-ignition internal combustion engine in which a total tension per piston of tensions applied to the piston ring is 100 N or less, the lubricating oil composition being a lubricating oil composition including a base oil, (A) a calcium-based detergent, at least one selected from (B1) a sodium-based additive and (B2) a magnesium-based additive, and (C) an ash-free sulfur-based additive in predetermined contents; a method for producing the lubricating oil composition; a spark-ignition internal combustion engine using the lubricating oil composition; and a method for lubricating the internal combustion engine.

The disclosure provides (i) a lubricating oil composition including a base oil (A) with a kinematic viscosity at 100 C. of 8.2-12.6 mm.sup.2/s and a saturated hydrocarbon content of 90% by mass or more, a metallic detergent (B) and a zinc dithiophosphate (C), wherein a content of the metallic detergent (B) is 2.5 mmol or more as a soap content concentration per 100 g of the composition, a phosphorous content is 200-1000 mass ppm, and a base number is 7.5 mg KOH/g or more, and (ii) a lubricating oil composition including the base oil (A), the metallic detergent (B), the zinc dithiophosphate (C) and an amine-based antioxidant (E), wherein a content of the amine-based antioxidant (E) is 0.3% by mass or more in terms of total content of the composition, a base number is 6.5 mg KOH/g or more, and a phosphorous content is 200-1000 mass ppm.

A low-phosphorus lubricating composition having less than 600 ppm phosphorus, comprising at least 85 weight % of a lubricating base blend, and an additive comprising the following, as weight % of the total composition: (1) an organomolybdenum component comprising: (a) an organomolybdenum complex, and (b) a molybdenum dithiocarbamate, the organomolybdenum component being present at an amount which provides about 400-800 ppm Mo; (2) (iso-octyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), at about 0.25-1.5%; (3) a dithiocarbamate component comprising (a) methylene-bis-dialkyldithiocarbamate and (b) said molybdenum dithiocarbamate, at a total dithiocarbamate component of about 0.6-1.2%; and (4) an alkylated diphenyl amine, at about 0.5-1.5%.