A lubricating oil composition for an internal combustion engine has a HTHS viscosity at 150° C. of 2.25 to <2.55 mPa.Math.s and includes: (A) a lubricating base oil including (a) mineral base oil(s) and/or (a) synthetic base oil(s), and having a kinematic viscosity at 100° C. of 3.8-4.6 mm.sup.2/s; (B) 1000-2000 mass ppm, in terms of metal content, of a metallic detergent including (a) metal salicylate detergent(s), and delivering ≥10 mmol/kg of total salicylate soap base per kilogram of the composition; (C) 1.0 to 4.0 mass % of a comb-shaped poly(meth)acrylate having a Mw of 350,000-1,000,000 and a PDI of ≤4.0; and (D) 100-1000 mass ppm, in terms of nitrogen, of a succinimide dispersant including (i) (a) non-modified succinimide dispersant(s) and/or (ii) (a) boric acid-modified succinimide dispersant(s), wherein the (i) and the (ii), in total, deliver 70 mass % of total nitrogen content of the component (D).

A lubricating composition suited to use for lubricating a hydraulic system includes an oil of lubricating viscosity and a compound comprising a polyolefin-substituted bridged hydroxyaromatic compound or metal salt thereof, wherein the wherein the polyolefin is derived from a isobutylene having a number average molecular weight of 150 to 800.

A method for lubricating an internal combustion engine, the method including: supplying a lubricating oil composition to a cylinder of an internal combustion engine, wherein the internal combustion engine has a mean effective pressure of no less than 1.3 MPa, wherein an integrated intensity ratio of peaks of CaO in a X-ray diffraction spectrum of an ash is no more than 16.5%, the ash being obtained by incinerating the lubricating oil composition in an air at 950° C.

The disclosed technology provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, a 300 TBN or higher alkaline earth metal sulfonate detergent having a metal ratio of 10 to 40, an alkaline earth metal sulfonate detergent having a metal ratio of 3 to 9, and a TBN of 81 to 180 mg KOH/g, wherein the sulfonate detergents provide a total amount of sulfonate substrate of 1 wt % to 3 wt % of the lubricating composition, 0.1 to 1.2 wt % of antioxidant, wherein at least 20 wt % of the antioxidant is a phenolic antioxidant, a borated compound present in an amount to deliver 25 ppm to 300 ppm of boron, the lubricating composition has a sulfated ash content of 0.5 wt % to not more than 1.5 wt %, and the lubricating composition has a TBN of 6.5 to 15 mg KOH/g.

Provided are a lubricating oil composition used in a diesel engine equipped with a forced-induction compressor, containing a base oil (A) containing a poly--olefin (A1), and a viscosity index improver (B) having an SSI (shear stability index) of 20 or less, having a distillation amount of a light fraction of 496 C. or less in a gas chromatography distillation test of less than 80% by volume, having a high retention of the effect of suppressing the formation of deposits that may occur inside the compressor, and being capable of retaining a high efficiency of the compressor for a long period of time, in the use thereof in a diesel engine equipped with a forced-induction compressor having an outlet temperature of the compressor becoming a high temperature reaching 190 C. or more, and a method for using the lubricating oil composition.

A lubricating oil composition for an internal combustion engine includes: a lubricant base oil including at least one mineral base oil, at least one synthetic base oil, or any combination thereof, and having a kinematic viscosity at 100 C. of 3.0 to 4.0 mm.sup.2/s and a NOACK evaporation loss at 250 C. of no more than 15 mass %; (A) a calcium-containing metallic detergent in an amount of no less than 1000 mass ppm and less than 2000 mass ppm in terms of calcium; (B) a magnesium-containing metallic detergent in an amount of 100 to 1000 mass ppm in terms of magnesium; (G) a zinc dialkyl dithiophosphate in an amount of no less than 600 mass ppm in terms of phosphorus; and optionally (C) a viscosity index improver in an amount of no more than 5 mass %.

A lubricating system includes a machine configured to operate in a first operating state and a second operating state; and a heat activated polymer material applied to at least a part of the machine and to remain solid during the first operating state and to soften upon being heated in the second operating state to lubricate the machine. The heat activated polymer material may soften due to increased friction incurred by the machine in the second operating state. A heating element may be operatively connected to any of the machine and the heat activated polymer material. The heat activated polymer material may soften due to being heated by the heating element in the second operating state. An injector may apply the heat activated polymer material to the machine. A channel may direct a flow of the heat activated polymer material as it softens in the second operating state.

A lubricating oil composition for a push-belt continuously variable transmission includes: (A) a lubricant base oil including at least one wax-isomerized base oil, and having a specific kinematic viscosity and a specific viscosity index; (B) a poly(meth)acrylate having a specific weight average molecular weight; (C) a boron-containing succinimide compound; (D) a borate ester compound; and (E) an overbased calcium detergent, wherein the composition has a kinematic viscosity at 40 C. of no more than 25 mm.sup.2/s; a viscosity index of no less than 180; and the ratio of a boron content to a calcium content of 0.5 to 1.5.

A lubricating composition suited to use for lubricating a hydraulic system includes an oil of lubricating viscosity and a compound comprising a polyolefin-substituted bridged hydroxyaromatic compound or metal salt thereof, wherein the wherein the polyolefin is derived from a isobutylene having a number average molecular weight of 150 to 800.

The invention provides a method of lubricating a 2-stroke marine diesel cylinder liner with a lubricating composition having a total base number of 10 to 25 mg KOH/g. The invention further provides a lubricating composition for lubricating the 2-stroke marine diesel cylinder liner.