There are 4 kind of crude oil. Look that shit up. Oil engineering is a masters degree level dig.
Most of the garbage crude left here can't be burned in American cars and trucks. We can't burn fracked crude products (we can with very expensive refining, but we for the most part don't), we can only export it to places who can refine and use Light sour, Heavy sweet, heavy sour crude, places running 2 stroke level engines and slightly better. Thus we are a "net exporter" of crude. American fuel must be made from Light Sweet crude. It has to do with the sulfur content. Emissions shit. I've been bitching about this for 30+ years.