Something I was wondering about recently

If it's oily and has a smell of diesel fuel to it, it's a good chance that's exactly what happened. Some noephyte fuel hauler mixed the fuel. It DOES happen. You should have let the station owner know. And Shell, Chevron and Texaco, all use the same additives, just in different ratios. Exxon ? I never touch the stuff. Everytime I hauled it, it always smelled funny. The gas I hauled directly from their rack always looked burned and had a smoky color to it. Never had any problems with Marathon's gas.