The thing that confuses what oil is doing relative to other real assets is this variable measure we use, paper money. If we all used a stable currency then we would have a clearer picture, but even gold is not completely stable because it ebbs and flows given the confidence or lack thereof in the various depreciating national or supranational debt instruments we call money, and it is somewhat controlled by the coordinated efforts of the government sponsored central banks.

Perhaps the one of the better way to see if oil is becoming more expensive relative to other real assets would be to compare it to a commodity index. You can be sure that until there is a financial collapse, all the currencies will depreciate because they are all being expanded, just at different rates at different times. If I had to pick one measure out of those you presented, I would pick gold or one of the currencies of the remaining countries which produce oil in excess of local demand.

Plunder and control imposed by force is the trademark of government. This is why it must be severely limited to insure maximum freedom.