2003 Ford Thunderbird Owner Guide 2nd Printing - Page 170
2003 Ford Thunderbird Manual
Page 170 highlights
Maintenance and Specifications 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. We do not recommend the use of gasolines labeled as "Premium" in high altitude areas that are sold with octane ratings of less than 91. 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. 91 170 2003 Thunderbird (tbr) Owners Guide (post-2002-fmt) USA English (fus)