Nowhere. Even Europeans have to buy oil inUS$ due to the Bretton Woods Treaty. The Russians & Chinese would buy/sell oil in gold or their own currencies in a heartbeat if that wouldn't get them sideways with the US fed.
Exactly. Saddam Hussein tried to start an oil exchange that wasn't denominated in USD, and then he was taken out of power by the US government.
Iran started saying they were going to do the same thing, and again we heard the war drums beat again.
The US Government is pretty clear on their stance about this...