Crude oil, in dollars per barrel, source: tradingeconomics.com:
Crude oil, in dollars per barrel, adjusted for inflation (M2 adjusted):
Crude oil, in dollars per barrel, adjusted for inflation and (diminishing) income of americans:
Note: In the year 2008 there was an extreme short term spike in oil price reaching 160 dollars per barrel. It is not visible in the chart, because I use annual data (of the last day of the year). But the long term trend is clear and unaffected.