The samples of diesel oils from Atas, Batman, and Iran sources, gasoline, and used lubricant oil were used in this work. Diesel fuels are composed of hydrocarbons, with between 12 and 25 carbon atoms in a chain as well as a smaller amount of sulfur, nitrogen, oxygen, and metal compounds. Diesel oil is useful for diesel and heating fuels. It is catalytically pyrolyzed and cracked to naphtha and may be steam cracked to olefins. The yields of distillation products for the samples increase with increasing temperature. The yield of distillation product sharply increases between 455 K and 649 K from 11.2-95.0 vol% for Atas diesel oil. The Atas diesel oil is considerably more volatile than used lubricant oil distillation products. The yields of distillation products for the diesel oil samples increase with increasing temperature. The increase of distillation products is highest for the Iran diesel oil sample.