2010 Ford Mustang Owner's Manual - Page 281

Maintenance and Specifications Your vehicle was not designed to use fuel or fuel additives with metallic compounds, including manganese-based additives. Note: Use of any fuel other than those recommended may cause powertrain damage, a loss of vehicle performance, and repairs may not be covered under warranty. Octane recommendations Your vehicle is designed to use "Regular" unleaded gasoline with a pump (R+M)/2 octane rating of 87. Some stations offer fuels posted as (R+M)/2 METHOD "Regular" with an octane rating below 87, particularly in high altitude areas. Fuels with octane levels below 87 are not recommended. Do not be concerned if your engine sometimes knocks lightly. However, if it knocks heavily under most driving conditions while you are using fuel with the recommended octane rating, see your authorized dealer to prevent any engine damage. 87 Octane recommendations (4.6L V8 engine) Your vehicle will run normally on 87 octane regular fuel without damaging the engine, but premium fuel with an octane rating of 91 (R+M)/2 or higher is recommended for best overall performance. For Shelby GT500 octane requirements, see the Shelby GT500 Supplement. Fuel quality If you are experiencing starting, rough idle or hesitation driveability problems during a cold start, try a different brand of "Regular" unleaded gasoline. Premium unleaded gasoline is not recommended for vehicles designed to use "Regular" unleaded gasoline because it may cause these problems to become more pronounced. If the problems persist, see your authorized dealer. Do not add aftermarket fuel additive products to your fuel tank. It should not be necessary to add any aftermarket products to your fuel tank if you continue to use high quality fuel of the recommended octane rating. These products have not been approved for your engine and could cause damage to the fuel system. Repairs to correct the effects of using an aftermarket product in your fuel may not be covered by your warranty. Many of the world's automakers approved the World-Wide Fuel Charter that recommends gasoline specifications to provide improved 281