The great thing about gold, in the oil trade, is that it is impossible to trace.

During the 1930's a lot of oil trading was done with gold bars. The great depression was on and no one wanted dollars, but that is entirely different from the reasons gold is being used to buy oil today.

However, I long ago heard rumors from the old guys that oil from areas controlled by Japan was being imported to the US in violation of some treaty or something, and the fear of the dollar falling was used as an excuse to cover up the payment in gold. Since there was no check to clear the gold could go anywhere to pay for oil that had come from anywhere. When you are dealing with that kind of money a lot of ethics goes right out the window.

This all stopped a few months before Pearl Harbor, but by then Japan needed all the oil it could get its' hands on and no one questioned why they were not sending it to the US. No one in the oil business, anyway.