A lubricating oil composition may include a base oil (A), succinimide (B) which has not been modified with boron, succinimide (C) modified with boron, a metallic detergent (D), and an antioxidant (E), wherein the ratio of the content of boron atoms derived from ingredient (C) to the content of nitrogen atoms derived from ingredients (B) and (C), B/N, is 0.30 or less by mass, the lubricating oil composition satisfying requirement (I) and/or requirement (II). Requirement (I): Ingredient (D) includes a metallic detergent (D1) having a base value less than 100 mgKOH/g. Requirement (II): Ingredient (E) includes an amine-based antioxidant (E1), the content of ingredient (E1) being 1.00 mass % or less.

A lubricating oil composition containing a base oil (A), a comb-shaped polymer (B), and an olefin-based copolymer (C), wherein a content of the component (B) is more than 0.80 mass % based on the total amount of the lubricating oil composition, a weight average molecular weight of the component (C) is 500,000 or more, and the lubricating oil composition has a viscosity index of 200 or more and a kinematic viscosity at 100° C. of 9.3 to 11.0 mm.sup.2/s.

A lubricating oil composition containing a base oil (A), a comb-shaped polymer (B), and an olefin-based copolymer (C), wherein a content of the component (B) is more than 0.80 mass % based on the total amount of the lubricating oil composition, a weight average molecular weight of the component (C) is 500,000 or more, and the lubricating oil composition has a viscosity index of 200 or more and a kinematic viscosity at 100° C. of 9.3 to 11.0 mm.sup.2/s.

A lubricating oil composition for agricultural machines, containing: at least one base oil selected from the group consisting of mineral oil-based base oils and synthetic oil-based base oils; and a polyalkyl methacrylate-based viscosity index improver having a weight average molecular weight of from 20,000 to 80,000, in which a kinematic viscosity at 100° C. is from 8.00 mm.sup.2/s to 10.00 mm.sup.2/s, a kinematic viscosity reduction rate at 100° C. in an ultrasonic shear stability test is 10.0% or less, and a Brookfield viscosity at −40° C. is 20,000 mPa.Math.s or less.

Provided are a lubricant composition for shock absorbers, a lubricant additive, and a method of adjusting friction characteristics of a lubricant composition for shock absorbers, each capable of satisfying both the operational stability and ride comfort. The lubricant composition for shock absorbers contains a base oil and a friction adjusting agent, the friction adjusting agent contains pentaerythritol esters, and the pentaerythritol esters contain a pentaerythritol tetraester and a pentaerythritol ester other than the pentaerythritol tetraester.

Provided are a lubricant composition for shock absorbers, a lubricant additive, and a method of adjusting friction characteristics of a lubricant composition for shock absorbers, each capable of satisfying both the operational stability and ride comfort. The lubricant composition for shock absorbers contains a base oil and a friction adjusting agent, the friction adjusting agent contains pentaerythritol esters, and the pentaerythritol esters contain a pentaerythritol tetraester and a pentaerythritol ester other than the pentaerythritol tetraester.

The disclosed technology provides alkylphenol-containing detergent having at least one unit (a) of an alkyl-substituted phenol wherein the alkyl group is derived from oligomers of an olefin compound containing 3 to 8 carbon atoms, wherein the polyolefin-derived alkyl group comprises at least 30 mol percent of an olefin with 4 or more carbon atoms. The invention further relates to a method of lubricating a mechanical device with the lubricant composition.

The disclosed technology provides alkylphenol-containing detergent having at least one unit (a) of an alkyl-substituted phenol wherein the alkyl group is derived from oligomers of an olefin compound containing 3 to 8 carbon atoms, wherein the polyolefin-derived alkyl group comprises at least 30 mol percent of an olefin with 4 or more carbon atoms. The invention further relates to a method of lubricating a mechanical device with the lubricant composition.

A lubricating oil composition including a base oil (A) containing an olefin-based polymer (A1), a viscosity index improver (B), and an imide-based dispersant (C), in which a first olefin-based polymer (A1-1) having a kinematic viscosity at 100° C. of 3.0 mm.sup.2/s or more is contained as the olefin-based polymer (A1), a second olefin-based polymer (A1-2) having a kinematic viscosity at 100° C. of less than 3.0 mm.sup.2/s is not contained as the olefin-based polymer (A1), a content of a resin component (B1) derived from the viscosity index improver (B) is 0.01% by mass or more based on a total amount of the lubricant composition, and a content of nitrogen atoms derived from the imide-based dispersant (C) is 0.06% by mass or more based on the total amount of the lubricant composition.

A lubricating oil composition which may contain a zinc dialkyl dithiophosphate, and whose color deterioration over time is alleviated. Such a lubricating oil composition may contain: a base oil (A); a zinc dialkyl dithiophosphate (B); and a sodium-based detergent (C). In such a lubricating oil composition, a content of zinc atoms may be 100 ppm by mass to 2,000 ppm by mass based on a total amount of the lubricating oil composition, and a content of sodium atoms may be 5 ppm by mass to 1,000 ppm by mass based on the total amount of the lubricating oil composition.