Isn't there a law that prevents that kind of thing, i don't exactly remember the "name" of the law but it has to do with, companies are suppose to be in competition, no monopoly.
But if that is the case then, let's say that Esso is selling at 92.5 why would let's say Shell not keep it at 89.9. No instead they jack up the price , wouldn't Shell make more money and sales if they kept their prices at 89.9.
Hopefully you guys understand what i'm trying to say here