Distillates (petroleum), heavy naphthenic; Unrefined or mildly refined baseoil; [A complex combination of hydrocarbons produced by vacuum distillation of the residuum from atmospheric distillation of crude oil. 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 °F (19cSt at 40 °C). It contains relatively few normal paraffins.]