you cannot participate to 100 % in the actual future price of oil (which would be THE Oil Price the Guys are talking in the News. This is because of the "rollin over" effect. Oil is an so called "Contango" situation. This means your future is alwasys worth a bit more than the future of the next month resp. the spot price. Thats why you always lose about 1 % each month. This in addition to the managment costs of the ETF.
look at "Contango" in wikinvest.com