Your Rodeo is designed to run on 87 octane fuel. Adding higher octane fuel gives no benefit. If you've been running higher octane, some say that your computer "gets used to it" and that you can't switch back. Thats a load of BS. The computer will just get used to using 87 again. The only thing octane is for is to prevent knocking and pinging. If you're not knocking and pinging on 87, then higher octane is a waste of money.