Nitrogen-Functionalized Olefin Polymers for Driveline Lubricants

A lubricant composition for a driveline system comprising:

• (a) an oil of lubricating viscosity having a kinematic viscosity at 100° C. of about 2 to about 10 cSt;
• (b) 3 to 50 wt % of the composotion of at least one viscosity modifier comprising a grafted copolymer that is an oil soluble ashless condensation reaction product of an olefin polymer, having a number average molecular weight (“Mn”) as measured by Gel Permeation Chromatography (“GPC”) with a polystyrene standard of about 1000 to about 10,000, comprising carboxylic acid functionality or a reactive equivalent thereof grafted onto the polymer backbone, with an amine, provided that if the olefin polymer is an ethylene/propylene copolymer, then said amine is one of an aliphatic amine, a heterocyclic amine or an aromatic amine;
• (c) at least one oil soluble phosphorus containing antiwear agent
• wherein the lubricant is for an automotive gear and has a sulfer content of about 100 to about 40,000 ppm and a phosphorus content of about 200 ppm to about 3000 ppm.