Distillates (petroleum), clay-treated heavy naphthenic is a complex combination of hydrocarbons resulting from treatment of a petroleum fraction with natural or modified clay in either a contacting or percolation process to remove the trace amounts of polar compounds and impurities present. It consists of hydrocarbons having carbon numbers predominantly in the range of C20 through C50 and produces a finished oil with a viscosity of at least 100 SUS at 100.degree.F (19cSt at 40.degree.C). It contains relatively few normal paraffins.
