Method for improving low-temperature fluidity of lubricating oils using high-and-low-molecular weight polymer additive mixtures

A method for maintaining low temperature fluidity of a lubricating oil composition comprising adding from 0.03 to 3 percent, based on total lubricating oil composition weight, of a first [P1] and a second [P2] polymer to the lubricating oil composition wherein:

• (a) the first polymer [P1] comprises monomer units selected from one or more of vinylaromatic monomers, α-olefins, vinyl alcohol esters, (meth)acrylic acid derivatives, maleic acid derivatives and fumaric acid derivatives, and has a weight average molecular weight from 250,000 to 1,500,000;
• (b) the second polymer [P2] comprises monomer units selected from one or more of vinylaromatic monomers, α-olefins, vinyl alcohol esters, (meth)acrylic acid derivatives, maleic acid derivatives and fumaric acid derivatives, and has a weight average molecular weight from 10,000 to 1,500,000;
• (c) the first polymer [P1] has a weight average molecular weight at least 50,000 greater than that of the second polymer [P2];
• and
• (d) the first and second polymers are combined in a weight ratio ([P1]/[P2]) of 5/95 to 75/25.

A concentrate for use in lubricating oil compositions comprising a lubricating oil diluent and from 30 to 70 percent, based on weight of the concentrate, of a first [P1] and a second [P2] polymer, wherein:

• (a) the first polymer [P1] comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 30 to 75 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and 25 to 70 percent monomer units, selected from one or more (C16-C24)alkyl (meth)acrylates, based on total first polymer weight, and has a weight average molecular weight from 250,000 to 1,500,000;
• (b) the second polymer [P2] comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 90 to 100 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and zero to 10 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates, based on total second polymer weight, and has a weight average molecular weight from 10,000 to 1,500,000;
• (c) the first polymer [P1] has a weight average molecular weight at least 50,000 greater than that of the second polymer [P2];
• and
• (d) the first and second polymers are combined in a weight ratio ([P1]/[P2]) of 5/95 to 75/25.

A lubricating oil composition comprising a lubricating oil and from 0.03 to 3 per cent, based on weight of the lubricating oil composition, of a first [P1] and a second [P2] polymer wherein:

• (a) the first polymer [P1] comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 30 to 75 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and 25 to 70 percent monomer units, selected from one or more (C16-C24)alkyl (meth)acrylates, based on total first polymer weight, and has a weight average molecular weight from 250,000 to 1,500,000;
• (b) the second polymer [P2] comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 90 to 100 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and zero to 10 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates, based on total second polymer weight, and has a weight average molecular weight from 10,000 to 1,500,000;
• (c) the first polymer [P1] has a weight average molecular weight at least 50,000 greater than that of the second polymer [P2];
• (d) the first and second polymers are combined in a weight ratio ([P1]/[P2]) of 5/95 to 75/25;
• (e) the lubricating oil comprises a base fluid selected from one or more of API Group I and Group II base stocks;
• and
• (f) the lubricating oil composition comprises from 0.1 to 20 percent, based on total lubricating oil composition weight, of auxiliary additives selected from one or more viscosity index improvers, antiwear agents, antioxidants, dispersants, detergents, friction modifiers, antifoam agents, extreme pressure additives and corrosion inhibitors.