Ok,If oil companies only operate at 90% , because they have to do maintence on the other 10% ,isn't that operating at 100% of thier capacity if the 10% is always of off line.Seems like easy math to me.
If they refine a 900 barrels a day and must keep the maintence going,then to refine 1000 barrels a day,they have to have a capacity to refine 1100 barrels a day in rounded off terms.
In a stretch, theoretically,they could never reach the 100% design capacity ,so in reality theyare producing 100% of what they can.
Again, even considering retrofitting and upgrading, they will not build new refineries that would reduce the price of gas. Retrofitting/upgrading does not significantly increase refinery capacity.
In addition,they might not set the price of oil, but they reap the profit of it's increase.
Don't take my word for it any more than I would expect you to take what SteveNO said;
look at the ACTUAL DATA and decide for yourselfhttp://tonto.eia.doe.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=WPULEUS3&f=W 
