The problem with investing in oil using ETFs is the strong contango of oil futures. Today it is at about 8$ per year. This means that even if the spot oil price goes up 25% during a year, the ETF is still flat or even slightly negative. In fact you could always make a lot of money by shorting oil ETFs, but not by going long oil. Oil is very volatile. Prices can make huge unpredictable jumps on political or terror events. I tried to backtest strategies with oil ETFs, but I was never able to achieve good results.