The refining industry could have adopted the motto “e pluribus unum” had it not been taken already. Which are the pluribus and which one is the unum, you ask? Each refined product of a given grade and specification is an unum, a singular and fungible product that can be used interchangeably by consumers worldwide. Even though refiners endlessly claim their gasoline is better than the competition’s, those differences are a function of quality control at the refinery level and of additive packages from contract blenders.

The pluribus represents the wide range of crude oils refiners can process into those refined products. Crude oils come in a bewildering array of compositions characterized by their sulfur content, (“sour” for the 85 percent or so of the world’s crude oils that are high-sulfur; “sweet” for low-sulfur), specific gravity, metallic impurities, and content of various organic acids and waxes.