(57) Polymers having useful preparties as oil additives are obtained by incorporating additional functional monomer units into oil-soluble backbene polymers having linear carbon chains, especially ethylene-propylene copolymers and ethylene-propylene-diene tempolymers.
The first functional monomers have at least one nitrogen, sulphur and/or oxygen atom in a heterocyclic ring. preferably phenothiazine or the reaction product of phenothiazine and allyl glycidyl ether.
Optionally a second amine polymer (preferably N-vinylpyrrolidone) can be grafted on to the backbone polymer.
The polymers of the invention consitute dispersant, anti-oxidant, viscosity index improvers for lubricating oils, while the polymers containing both types of monomer unit are also useful as dispersant additives for fuel oils.