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  1. Octane Booster in place of Premium Fuel?

    Fuel Economy and Alternative Fuels
    Hello, I have an 09 Forester XT. I have determined that I at least want to put 91 octane in my forester, but I am looking to save some money. Has anyone tried octane booster with mid-grade or regular fuel for their Subaru Turbo? Theoretically can I mix half and half of 89 (mid-grade) and...