Oil-soluble hydrolyzed anionic-graft polymer of ethylene-propylene copolymer and anionically polymerizable nitrile monomer and derivatives thereof having utility as multifunctional V. I. improver for lubricating oils

A lubricating oil composition comprising a major amount of mineral lubricating oil and about 0.1 to 10 wt. % of an oil soluble hydrolyzed anionic-graft polymer having a number average molecular weight in the range of about 1,00 to 500,000 while containing in the range of about 0.005 to 2 wt.% nitrogen and being useful as an oil additive having dispersancy properties, said anionic-graft polymer being a graft polymer of:

• 1. an anionically polymerizable monomer containing in the range of about 3 to 24 carbon atoms and at least one electron withdrawing group in such proximity to an olefinic bond that said bond is activated, said monomer being a nitrile monomer of the formula:
• ##STR7## wherein R.sup.v is hydrogen or lower alkyl up to about 12 carbons, X is selected from the group consisting of hydrogen, halogen, cyano and lower alkyl up to 6 carbons;
• and
• 2. an anionic of an oxidized ethylene copolymer comprising about 20 to 80 mole % ethylene and about 20 to 80 mole % propylene;
• said anionic graft polymer being either acid or base hydrolyzed.

A process of preparing a hydrolyzed anionic-graft polymer comprising the steps of:

• 1. contacting an oxidized ethylene copolymer comprising about 20 to 80 mole % ethylene and about 20 to 80 mole % propylene, having an oxygen content of from about 0.005 to 6% based on the weight of said copolymer, with an alkyl-lithium compound of from 3 to 10 carbons under anhydrous conditions and inert atmosphere for a period of between 1 and 25 hours and at a temperature between 20.degree. and 100.degree. C.;
• whereby an anion of said oxidized ethylene copolymer is produced;
• 2. contacting said anion with an anionically polymerizable monomer at a temperature between about 0.degree. and about 100.degree. C. and for a period of between about 0.2 and 15 hours in the presence of a base whereby an anionic-graft polymer is produced, and wherein said anionically polymerizable monomer is a nitrile monomer of the formula:
• ##STR8## wherein R.sup.v is hydrogen or lower alkyl, X is selected from the group consisting of hydrogen, halogen, cyano and lower alkyl;
• and
• 3. hydrolyzing with acid or base.