The present invention provides processes for making a bimodal solid polymer composition suitable for use as a viscosity index improver. Ethylene and an alpha-olefin comonomer are polymerized in the presence of a metallocene catalyst to form first and second copolymers, in series or parallel reactors, which are combined to form an intimate blend of relatively high and relatively low ethylene content copolymers in the solvent use. The composition can be further grafted and derivatized to provide a viscosity index improver, the composition being produced directly with the correct viscosity, without the need for additional blending, shearing or masticating steps.