Oil price is monotonically rising, right now is approaching 110$/barrel while just a bunch of years ago it was around 70$. At the same time the $/€ exchange rate is increasing, that is a single euro can buy more and more dollars. Oil market is based on dollars, so comparing the rate exchange and the oil price we can determine whether in Europe the oil price in € should raise or fall. According to this article (in Italian) written by Massimiliano Marzo (who covers an undefined role at Bologna University) oil price and $/€ exchange rate are rather correlated, apparently to keep a steady level so that the oil producers maintain the same value per barrel regardless of the dollar depreciation.