This method is for determining the distillation range of heavy petroleum oils. It is applicable to petroleum products whose boiling range extends above that of kerosine, e.g., crude, gas and fuel oils. The method differs from ASTM D 86 in that a 200-mL flask is used and the distillation apparatus is gas-fired. Coke residue is determined from a separate distillation that is continued past the thermal decomposition point. The test is particularly useful in estimating gasoline, kerosine and/or distillate content, and the coking characteristics of these oils.