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 grease composition which contains a base oil (A), a urea-based thickener (B), a sarcosine derivative (C), and a fatty acid zinc salt (D), wherein particles containing the urea-based thickener (B) in the grease composition satisfies Requirement (I). The base oil (A) is a blended base oil containing a high viscosity hydrocarbon-based synthetic oil having a specific kinematic viscosity (A1). A low viscosity hydrocarbon-based synthetic oil having a specific kinematic viscosity (A2). An ultra-high viscosity hydrocarbon-based synthetic oil has a number average molecular weight (Mn) of 2,500 to 4,500 and a specific kinematic viscosity (A3). A 40° C. kinematic viscosity of the base oil (A) is 500 mm.sup.2/s to 1,500 mm.sup.2/s. A viscosity index of the base oil (A) is 140 or more. A content of the fatty acid zinc salt (D) is 10 mass % to 20 mass % based on a total amount of the grease composition.

A defoaming agent obtainable by a process that includes: polymerizing (A) at least one polymerizable monomer in a composition, the composition comprising (C) a solvent and (B) at least one non-polymerizable polysiloxane dissolved in the (C) solvent, wherein the component (A) optionally comprises at least one Si-atom-containing monomer in an amount of less than 10 mass % on the basis of the total mass of the component (A).

A defoaming agent obtainable by a process that includes: polymerizing (A) at least one polymerizable monomer in a composition, the composition comprising (C) a solvent and (B) at least one non-polymerizable polysiloxane dissolved in the (C) solvent, wherein the component (A) optionally comprises at least one Si-atom-containing monomer in an amount of less than 10 mass % on the basis of the total mass of the component (A).

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.

Provided is an engine oil lubricant composition with improved fuel efficiency. The engine oil lubricant composition may include: a polyalpha olefin base oil component an amount of about 50 wt % to about 90 wt % based on a total weight of the engine oil lubricant composition, wherein the polyalpha olefin base oil component is a Group IV base oil and has a Noack volatility of about 12.5% to about 15%; a Group II base oil component in an amount of about 0.1 wt % to about 50 wt % based on the total weight of the engine oil lubricant composition. The engine oil lubricant composition may have (i) a kinematic viscosity at 100° C. of about 10 cSt or less, (ii) a high temperature high shear viscosity at 150° C. of about 2.2 cP or less, and (iii) a Noack volatility of about 20% or less.

A lubricating oil composition may be capable of satisfactorily exhibiting sludge prevention properties and wear resistance evaluated by scoring resistance and seizure resistance over a long period of time. Such a lubricating oil composition may contain: a base oil (A); a hindered phenol-based antioxidant (B); one or more imide compounds (C) selected from the group consisting of a monoimide compound (C1) and a bisimide compound (C2); and an extreme pressure agent (D), in which the hindered phenol-based antioxidant (B) is 2,6-di-tert-butylphenol, the monoimide compound (C1) is one or more selected from the group consisting of an alkenyl succinic monoimide compound and an alkyl succinic monoimide compound, and the bisimide compound (C2) is one or more selected from the group consisting of an alkenyl succinic bisimide compound and an alkyl succinic bisimide compound.