Abstract: A process for thermally cracking virgin or waste animal oils (tallow) into a diesel fuel product is provided. The thermal cracking process uses low cracking temperatures from 625 to 725° F. with ambient pressure and no catalyst to generate a column distilled fraction of diesel fuel mixed with light ends, the light ends being flashed off to produce a high quality #2 diesel fuel suitable for road use. The oils to be distilled are exposed to a heat exchanger with a skin temperature of 1750° F. generated by hot air produced by a thermal oxidizer. This results in the processed product going from a liquid to a liguid/gas during the pump around residence time of 3 to 5 seconds before moving up a distillation column as a gas to the desired finished product.