A lubricating oil composition for an internal combustion engine has a HTHS viscosity at 150° C. of 2.55-2.84 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 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 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).

Provided are a lubricating oil composition containing a mineral oil (1) having a kinematic viscosity at 100° C. of 2.5 mm.sup.2/s or more and 5 mm.sup.2/s or less, and a polymethacrylate (2) having a functional group containing an oxygen atom in the molecule while having a specific structural unit, which satisfies both high viscosity index and high shear stability, and a lubrication method and a transmission using the lubricating oil composition.

Provided are a lubricating oil composition containing a mineral oil (1) having a kinematic viscosity at 100° C. of 2.5 mm.sup.2/s or more and 5 mm.sup.2/s or less, and a polymethacrylate (2) having a functional group containing an oxygen atom in the molecule while having a specific structural unit, which satisfies both high viscosity index and high shear stability, and a lubrication method and a transmission using the lubricating oil composition.

A composition is obtained by mixing at least one oligomer A1, which is obtained by copolymerizing at least two monomers functionalized by diol functions with at least one second monomer, with at least one compound A2 having at least two boron ester functions. The compositions exhibit very varied rheological properties depending on the proportion of the compounds A1 and A2 used. A composition is also obtained by mixing at least one lubricating oil with such a composition of associative and exchangeable polymers, and the use of this composition to lubricate a mechanical part.

A composition is obtained by mixing at least one oligomer A1, which is obtained by copolymerizing at least two monomers functionalized by diol functions with at least one second monomer, with at least one compound A2 having at least two boron ester functions. The compositions exhibit very varied rheological properties depending on the proportion of the compounds A1 and A2 used. A composition is also obtained by mixing at least one lubricating oil with such a composition of associative and exchangeable polymers, and the use of this composition to lubricate a mechanical part.

A lubricant, including, by weight: 80-85 parts of a base oil; 1-2 parts of a methyl-silicone oil; 1-2 parts of polymethacrylate; 2-4 parts of pentaerythritol polyisobutylene succinate; 1-2 parts of di-n-butyl phosphite; 2-3 parts of butylhydroxytoluene; 2-4 parts of an ethylene-propylene copolymer; 1-2 parts of an alkenyl succinate; and 3-5 parts of copper nanoparticles. A method of preparing the lubricant includes: adding the base oil, the methyl-silicone oil, the polymethacrylate, the ethylene-propylene copolymer, the butylhydroxytoluene, the alkenyl succinate to a reactor, and stirring a resulting first mixture under normal temperature and pressure at 300-400 rpm for 3-4 hours, to yield a primary product; and adding the di-n-butyl phosphite, the pentaerythritol polyisobutylene succinate, and the copper nanoparticles to the primary product, and stirring a resulting second mixture at 150-250 rpm for 2-2.5 hours.

A lubricant, including, by weight: 80-85 parts of a base oil; 1-2 parts of a methyl-silicone oil; 1-2 parts of polymethacrylate; 2-4 parts of pentaerythritol polyisobutylene succinate; 1-2 parts of di-n-butyl phosphite; 2-3 parts of butylhydroxytoluene; 2-4 parts of an ethylene-propylene copolymer; 1-2 parts of an alkenyl succinate; and 3-5 parts of copper nanoparticles. A method of preparing the lubricant includes: adding the base oil, the methyl-silicone oil, the polymethacrylate, the ethylene-propylene copolymer, the butylhydroxytoluene, the alkenyl succinate to a reactor, and stirring a resulting first mixture under normal temperature and pressure at 300-400 rpm for 3-4 hours, to yield a primary product; and adding the di-n-butyl phosphite, the pentaerythritol polyisobutylene succinate, and the copper nanoparticles to the primary product, and stirring a resulting second mixture at 150-250 rpm for 2-2.5 hours.

A method of making a polymer having the structure (I): ##STR00001##
wherein L is a linking group, R is a hydrocarbon group or a substituted-hydrocarbon group, and x is 2 or more, preferably from 2 to 100, more preferably from 2 to 50; and wherein each {Q} is an identical polymer block or contains a plurality of polymer blocks. The method comprises reacting a di-halo initiator with a selected monomer one or more times and then reacting the resulting moiety with a dithiol compound of the structure HS—R—SH.