2004 Lincoln Navigator Owner Guide 4th Printing - Page 335

Maintenance and Specifications Choosing the right fuel Use only UNLEADED FUEL. The use of leaded fuel is prohibited by law and could damage your vehicle. Your vehicle was not designed to use fuel or fuel additives with metallic compounds, including manganese-based additives. Studies indicate that these additives can cause your vehicle's emission control system to deteriorate more rapidly. In Canada, many fuels contain metallic additives, but fuels free of such additives may be available; check with your local fuel dealer. Do not use fuel containing methanol. It can damage critical fuel system components. Repairs to correct the effects of using a fuel for which your vehicle was not designed may not be covered by your warranty. Octane recommendations Your vehicle is designed to use "Premium" unleaded gasoline with an (R+M)/2 octane rating of 91 or higher for optimum performance. (R+M)/2 METHOD The use of gasolines with lower octane ratings may degrade performance. The use of gasolines labeled as "Premium" in high altitude areas that are sold with octane ratings of less than 91 is 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 dealer or a qualified service technician to prevent any engine damage. 91 Fuel quality If you are experiencing starting, rough idle or hesitation driveability problems during a cold start, try a different brand of gasoline. If the problems persist, see your dealer or a qualified service technician. 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. Aftermarket products 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 335 2004 Navigator (nav) Owners Guide (post-2002-fmt) USA English (fus)