Abstract: A lubricating oil composition for an internal combustion engine, the composition including: a lubricating base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, the lubricating base oil having a kinematic viscosity at 100° C. of 4.0 to 4.5 mm2/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 on the basis of the total mass of the composition; and optionally (C) a viscosity index improver in an amount of less than 1 mass % on the basis of the total mass of the composition.

Abstract: 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 mm2/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 %.

Abstract: A lubricating oil composition for an internal combustion engine, the composition including: a lubricating base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, the lubricating base oil having a kinematic viscosity at 100° C. of 4.0 to 4.5 mm2/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 on the basis of the total mass of the composition; (B) a magnesium-containing metallic detergent in an amount of 100 to 1000 mass ppm in terms of magnesium on the basis of the total mass of the composition; and optionally (C) a viscosity index improver in an amount of less than 1 mass % on the basis of the total mass of the composition.

Abstract: 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 mm2/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 %.

Abstract: A lubricating oil composition for an internal combustion engine, the composition including: a lubricating base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, the lubricating base oil having a kinematic viscosity at 100° C. of 4.0 to 4.5 mm2/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 on the basis of the total mass of the composition; and optionally (C) a viscosity index improver in an amount of less than 1 mass % on the basis of the total mass of the composition.

Abstract: A lubricating oil composition for an internal combustion engine, the composition including: a lubricating base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, the lubricating base oil having a kinematic viscosity at 100° C. of 4.0 to 4.5 mm2/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 on the basis of the total mass of the composition; (B) a magnesium-containing metallic detergent in an amount of 100 to 1000 mass ppm in terms of magnesium on the basis of the total mass of the composition; and optionally (C) a viscosity index improver in an amount of less than 1 mass % on the basis of the total mass of the composition.

Abstract: A lubricating oil composition for an internal combustion engine including: (A) a lubricant base oil having a kinematic viscosity at 100° C. of 2 to 8 mm2/s and having an aromatic content of no more than 10 mass %; (B) a metallic detergent including: (B1) a metallic detergent overbased with calcium carbonate; and (B2) a metallic detergent overbased with magnesium carbonate; and (C) a molybdenum sulfide dithiocarbamate or a molybdenum oxysulfide dithiocarbamate, wherein the composition has, on the basis of the total mass of the composition, a calcium content of no more than 1500 mass ppm, a magnesium content of no less than 300 mass ppm, and a molybdenum content of no less than 600 mass ppm; and the composition has an HTHS viscosity at 150° C. of no more than 2.7 mPa·s.

Abstract: The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a core portion and three or more arm portions, wherein each of the arm portions consists of a polymer chain comprising a structural unit represented by the following formula (1), and one end of the polymer chain is bonded to the core portion, and wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less. [R1 represents hydrogen or a methyl group, and R2 represents a C1 to C36 alkyl group.

Abstract: The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a core portion, and three or more arm portions, wherein each of the arm portions consists of a polymer chain comprising a structural unit represented by formula (1) and a structural unit represented by formula (2) and one end of the polymer chain is bonded to the core portion, and wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less. [R1 represents hydrogen or a methyl group, and R2 represents a group represented by formula (3), and R3 represents a C1 to C18 alkyl group that is straight-chain or has a branch having 5 or less carbon atoms: m and n are integers which satisfy m?5, n?4, and m+n?31.

Abstract: The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a polymer chain comprising a structural unit represented by the following formula (1), wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less. [In the formula (1), R1 represents hydrogen or a methyl group, and R2 represents a C1 to C36 alkyl group.

Abstract: A lubricating oil composition comprising a lubricating base oil having a kinematic viscosity at 100° C. of 1 to 10 mm2/s, and a poly(meth)acrylate viscosity index improver containing a structural unit represented by the formula (1) in a proportion of 30 to 90 mol % and having a hydrocarbon main chain ratio of 0.18 or less: wherein R1 represents hydrogen or a methyl group, and R2 represents a linear or branched hydrocarbon group having a carbon number of 6 or less.

Abstract: The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a core portion and three or more arm portions, wherein each of the arm portions consists of a polymer chain comprising a structural unit represented by the following formula (1), and one end of the polymer chain is bonded to the core portion, and wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less. [R1 represents hydrogen or a methyl group, and R2 represents a C1 to C36 alkyl group.

Abstract: An engine oil composition comprising: a lubricating base oil having a kinematic viscosity at 100° C. of 1 to 5 mm2/s; a poly(meth)acrylate viscosity index improver containing a structural unit represented by the formula (1) in a proportion of 30 to 90 mol % and having a PSSI in an ultrasonic shear test of 15 or less; and a friction modifier, the engine oil composition has a kinematic viscosity at 100° C. of 4 to 8 mm2/s, and an HTHS viscosity at 150° C. of less than 2.

Abstract: A lubricating oil composition comprising a lubricating base oil having a kinematic viscosity at 100° C. of 1 to 10 mm2/s, and a branched poly(meth)acrylate viscosity index improver containing a structural unit represented by the following formula (1) in the proportion of 30 to 90 mol % and having a branching degree of 0.1 to 8.0: wherein R1 represents hydrogen or a methyl group, and R2 represents a linear or branched hydrocarbon group having a carbon number of 6 or less.

Abstract: The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a polymer chain comprising a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), wherein Mw is 100000 or more, and Mw/Mn, is 1.6 or less. [R1 represents hydrogen or a methyl group, and R2 represents a group represented by the following formula (3), and R3 represents a C1 to C18 alkyl group that is straight-chain or has a branch having 5 or less carbon atoms. m and n are integers which satisfy m?5, n?4, and m+n?31.

Abstract: A system for treating a selenium-containing liquid includes a concentration measurement element 15 for measuring the concentration of peroxodisulfuric acid and the concentration of tetravalent selenium in the selenium-containing liquid; a setting element 21 for setting the feed amount of bivalent manganese based on the concentrations of peroxodisulfuric acid and tetravalent selenium, and a reaction rate constant ratio which is the ratio of a reaction rate constant in a reaction between bivalent manganese and peroxodisulfuric acid to a reaction rate constant in a reaction between tetravalent selenium and peroxodisulfuric acid; and an addition element 14 for adding bivalent manganese to the selenium-containing liquid such that the bivalent manganese in the selenium-containing liquid is maintained in the above feed amount. Bivalent manganese is added to the selenium-containing liquid by the addition element, whereby oxidation of tetravalent selenium to hexavalent selenium is suppressed.

Abstract: It is to provide a process of treating a selenium-containing liquid which can inexpensively treat the selenium-containing liquid. The formation of selenate is inhibited by adding at least one selected from a group consisting of Ti and Mn into the selenium-containing liquid.

Abstract: It is to provide a process of treating a selenium-containing liquid which can inexpensively treat the selenium-containing liquid. The formation of selenate is inhibited by adding at least one selected from a group consisting of Ti and Mn into the selenium-containing liquid.