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.

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 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.

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.

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 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 %.

The present disclosure relates to methods of improving viscosity shear stability of a lubricating oil and lubricating oil composition comprising: a base oil of lubricating viscosity; an amount of one or more zinc dialkyl dithiophosphate compound(s);
wherein the lubricating oil composition has one or both of the following ratios: a) a ratio of KV40° C..sub.fresh to a weight % of zinc contributed by the one or more zinc dialkyl dithiophosphate compound(s) based on a total weight of the lubricating oil composition, of greater than 510, wherein KV40° C..sub.fresh is the kinematic viscosity of the fresh lubricating oil composition at 40° C.; and b) a ratio of KV40° C..sub.fresh to a weight % of phosphorus contributed by the one or more zinc dialkyl dithiophosphate compound(s) based on a total weight of the lubricating oil composition, of greater than 560, wherein KV40° C..sub.fresh is the kinematic viscosity of the fresh lubricating oil composition at 40° C.