C.sub.2 -C.sub.5 olefin oligomer compositions as shear stable viscosity index improvers

摘要

Liquid hydrocarbon lubricant viscosity index improver compositions are disclosed having high shear stability. The compositions comprise the homopolymer or copolymer product of the oligomerization of C. sub.3 to C. sub.5 alpha-olefin or mixtures thereof, with or without ethylene as co- monomer. The process is carried out under oligomerization conditions in contact with a reduced valence state Group VIB metal catalyst on porous support. The viscosity index improver of the invention has a regio- irregularity of at least 20%, weight average molecular weight between 6, 000 and 30,000 and molecular weight distribution between 2 and 5.