A distillate material of 40 API has a volumetric average boiling point of 550F. The (molecular weight, Critical Temperature and viscosity at 122F CS) are Mw = 230, TC = 550 F, Mue = 2.7 cs = = = .a O Mw = 230, TC = 500 F, Mue = 5 CS = = = .b O