Looking for data, it appears as if I am wrong or at least not definitely correct.From what do you make that [oil getting cheaper] conclusion?
Because oil is subject to price spikes, it is difficult to find a trend. The following link could be taken as showing a downward trend with spikes or it could be taken as showing a rising trend. Please note that the price is back down to around 40 not at the 56 shown on the graph.
http://www.fintrend.com/ftf/images/charts/Oil_inflation_LG.htm
I believe that oil has a natural price of less than $15. When there is a crisis in the middle east, it spikes. I realize that you could also say that oil has a natural price of $40 and that when things calm in the middle it drops. I would bet that in 10 years, oil will be back under $15 inflation adjusted.
CBL