2003 Lincoln Aviator Owner's Manual - Page 308

Maintenance and Specifications after some fuel is used (fuel gauge drops below full). Once the fuel filler cap is properly secured, "CHECK/TIGHTEN FUEL CAP" will turn off after a short period of driving. If you must replace the fuel filler cap, replace it with a fuel filler cap that is designed for your vehicle. The customer warranty may be void for any damage to the fuel tank or fuel system if the correct genuine Ford or Motorcraft fuel filler cap is not used. The fuel system may be under pressure. If the fuel filler cap is venting vapor or if you hear a hissing sound, wait until it stops before completely removing the fuel filler cap. Otherwise, fuel may spray out and injure you or others. If you do not use the proper fuel filler cap, excessive pressure or vacuum in the fuel tank may damage the fuel system or cause the fuel cap to disengage in a collision, which may result in possible personal injury. Choosing the right fuel Use only UNLEADED FUEL. The use of leaded fuel is prohibited by law and could damage your vehicle. Do not use fuel containing methanol. It can damage critical fuel system components. Your vehicle was not designed to use fuel or fuel additives with metallic compounds, including manganese-based compounds containing MMT. 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 91 308 2003 Aviator f/k/a Navigator LS (231) Owners Guide (post-2002-fmt) USA English (fus)