[DickingAround]

You still need to use oil, but you don't have to use dollars. The support for dollars relies on a lot of things including the government and thus the military, which are big costs and oil consumes. If the dollar didn't rely on the military power of the US, why is the Bretton Woods meeting and the post war monetary policy so important to it's dominance (something practically no one disputes)? Why is it that the US seems to care so much about pricing oil in dollars? You don't need a tinfoil hat (as other comments suggest) to notice the US government has a strong interest in everyone using our currency and that where the gov has a strong interest, it also uses it's guns.