is a series of processes for converting crude oil and its fractions to finished petroleum products. Following distillation, a petroleum fraction may undergo one or more additional steps to purify or modify it. These refining steps include: thermal cracking, catalytic cracking, polymerization, alkylation, reforming, hydrocracking, hydroforming, hydrogenation, hydrogen treating, Hydrofining, solvent extraction, dewaxing, de-oiling, acid treating, clay filtration, and deasphalting. Refined lube oils may be blended with other lube stocks, and additives may be incorporated, to impart special properties; refined naphthas may be blended with alkylates, cracked stock or reformates to improve octane number and other properties of gasolines.