I hope you know that the big oil companies own 80-90% of the refineries in America. After oil get refined, it goes to distribution centers. At that point, it get shipped to all different gas station. Only at the station do they add some additives to differentiate their gas. So, if you don’t pour at BP/Arco, you might be punishing Chevron/Shell/etc refineries/distribution center. If you pour at a Shell, you might be supporting BP’s refineries/distribution centers.