Oil futures are normally priced in US Dollars.
The chart below is the ETF (Exchange Traded Fund) USO and it’s underlying value are several US oil futures.
USO is a great product for those who can’t take the risk trading futures, but another problem for non-US Dollar trades is the currency risk if you trade the USO ETF in US Dollars.
Below we see the price of USO (red line) US Dollars and the price of USO in EUR/USD (blue line) while at the bottom the exchange rate of the EUR/USD.
Of course the difference between the lines is the currency risk for non-US Dollar traders and it shows the importance to hedge US Dollar assets for non US Dollar traders.
Trading Forex in Baskets to diversify trading risk for both, speculative trading or hedging Forex risk by 


[...] In this post I like to answer the question I got about the earlier post of Oil in EUR http://blogs.fxstreet.com/forexhedge/2009/01/15/oil-in-euro/ [...]