Lubricant

A hydrogenated olefin oligomer consisting mainly of dimers of C.sub.12-18 predominantly alpha olefins having a viscosity above about 3.0 cs at 100.degree. C., a pour point below 0.degree. C. and low volatility such that less than 25 weight percent evaporates after two hours at 204.degree. C., said oligomer being suitable for use in crankcase lubricants for internal combustion engines, said oligomer being made by the process comprising contacting a C.sub.12-18 predominantly alpha olefin or mixture thereof, with the proviso that the average carbon number of said olefin or mixture thereof is at least 13, with a Friedel-Crafts catalyst at a temperature of about 20.degree.-200.degree. C. until the reaction mixture excluding monomer is predominantly dimer, distilling to remove monomer and hydrogenating.