This is my problem with your premise.
Can you proved Bush invaded "for oil"? Sure, American companies are gonna profit and more oil is gonna be available to the world market, but some Iraqis are gonna cash in too. And at least this will mean the end of the Oil for Food fiasco. It's not like we're going in, filling up drums with oil, and then bouncing.
In order to prove that the war was waged solely for oil, you would have to disprove all of the other given justifications: we thought they had WMD, humanitarian reasons, corrupt regime, etc.