2010 Ford Flex Owner Guide 2nd Printing - Page 364

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 3.5L V6 engine Your vehicle will run normally on 87 octane regular fuel. Premium fuel will provide improved performance. 3.5L V6 EcoBoost engine Your vehicle is designed to run on regular fuel with an octane rating of 87 or higher. For best overall performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel will be most noticeable in hot weather or in severe duty applications such as towing a trailer. 87 (R+M)/2 METHOD Some stations offer fuels posted as ЉRegularЉ with an octane rating below 87, particularly in high altitude areas. Fuels with octane levels below 87 are not recommended for either engine. Do not be concerned if your engine sometimes knocks lightly. However, if it knocks heavily while you are using fuel with the recommended octane rating, see your authorized dealer to prevent any engine damage. Fuel quality If you are experiencing starting, rough idle or hesitation driveability problems during a cold start, try a different brand of unleaded gasoline. 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. 364 2010 Flex (471) Owners Guide, 2nd Printing USA (fus)