Lubricating oil compositions

A method for lubricating a crankcase in an internal combustion engine comprising:

• using in said crankcase a lubricant composition comprising a mineral oil base stock and a lubricant additive in an amount sufficient to enhance the dispersability of particles in the lubricant composition, the lubricant additive comprising:
• (a) a first dispersant and a second dispersant each independently comprising at least one member selected from the group consisting of hydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines, and Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine;
• wherein the hydrocarbyl substituent of the first dispersant has a number average molecular weight ranging from about 1500 to about 2500 as determined by gel permeation chromatography,
• wherein the hydrocarbyl substituent of the second dispersant has a number average molecular weight ranging from about 800 to about 1200 as determined by gel permeation chromatography, and
• wherein the hydrocarbyl-substituent of at least one of the first and second dispersants comprises the polymerization product of a reaction mixture comprising (i) from about 55 to about 65 weight percent raffinate I stream and (ii) from about 35 to about 45 weight percent isobutylene, with the proviso that (i) and (ii) are different;
• and
• (b) a viscosity index improver comprising a substantially linear block copolymer having A number average molecular weight as determined by gel permeation chromatography ranging from about 50,000 to about 250,000, the block copolymer being derived from a conjugated diene monomer containing no less than 5 carbon atoms and a styrene monomer, wherein the block copolymer has a styrene content ranging from about 30 wt. % to about 40 wt. %, and an olefinic unsaturation ranging from about 0.5 wt. % to about 5 wt. %.

A method of reducing wear in an internal combustion engine comprising:

• using as the automatic transmission fluid for said engine a fluid composition comprising a mineral oil base stock and an additive in an amount sufficient to enhance the dispersability of particles in the lubricant composition, the additive comprising:
• (a) a first dispersant and a second dispersant each independently comprising at least one member selected from the group consisting of hydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines, and Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine;
• wherein the hydrocarbyl substituent of the first dispersant has a number average molecular weight ranging from about 1500 to about 2500 as determined by gel permeation chromatography,
• wherein the hydrocarbyl substituent of the second dispersant has a number average molecular weight ranging from about 800 to about 1200 as determined by gel permeation chromatography, and
• wherein the hydrocarbyl-substituent of at least one of the first and second dispersants comprises the polymerization product of a reaction mixture comprising (i) from about 55 to about 65 weight percent raffinate I stream and (ii) from about 35 to about 45 weight percent isobutylene, with the proviso that (i) and (ii) are different;
• and
• (b) a viscosity index improver comprising a substantially linear block copolymer having a number average molecular weight as determined by gel permeation chromatography ranging from about 50,000 to about 250,000, the block copolymer being derived from a conjugated diene monomer containing no less than 5 carbon atoms and a styrene monomer, wherein the block copolymer has a styrene content ranging from about 30 wt. % to about 40 wt. %, and an olefinic unsaturation ranging from about 0.5 wt. % to about 5 wt. %.

A method for lubricating moving parts in a drive train of an internal combustion engine comprising:

• using as the lubricating oil for said drive train a lubricant composition comprising a mineral oil base stock and a lubricant additive in an amount sufficient to enhance the dispersability of particles in the lubricant composition, the lubricant additive comprising:
• (a) a first dispersant and a second dispersant each independently comprising at least one member selected from the group consisting of hydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines, and Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine;
• wherein the hydrocarbyl substituent of the first dispersant has a number average molecular weight ranging from about 1500 to about 2500 as determined by gel permeation chromatography,
• wherein the hydrocarbyl substituent of the second dispersant has a number average molecular weight ranging from about 800 to about 1200 as determined by gel permeation chromatography, and
• wherein the hydrocarbyl-substituent of at least one of the first and second dispersants comprises the polymerization product of a reaction mixture comprising (i) from about 55 to about 65 weight percent raffinate I stream and (ii) from about 35 to about 45 weight percent isobutylene, with the proviso that (i) and (ii) are different;
• and
• (b) a viscosity index improver comprising a substantially linear block copolymer having a number average molecular weight as determined by gel permeation chromatography ranging from about 50,000 to about 250,000, the block copolymer being derived from a conjugated diene monomer containing no less than 5 carbon atoms and a styrene monomer, wherein the block copolymer has a styrene content ranging from about 30 wt. % to about 40 wt. %, and an olefinic unsaturation ranging from about 0.5 wt. % to about 5 wt. %.