Ford Town Car Owner's Manual page 244

3. Replace the fuel cap completely when you are
finished. Turn it clockwise 1/4 turn until it is
tight. It will click when it is fully tightened.
4. Push the fuel door closed.
WARNING
If you do not use the proper fuel cap,
the pressure in the fuel tank can
damage the fuel system or cause it to
work improperly in a collision.
NOTE: If you replace your fuel cap with an
aftermarket fuel filler cap, the customer warranty
may be void for any damage to the fuel tank
and/or fuel system.
Choosing the Right Fuel
Use only UNLEADED FUEL. The use of leaded fuel
is prohibited by law and could damage your vehicle.
The damage may not be covered by your warranty.
Your vehicle was not designed to use fuel
containing manganese-based additives such as MMT.
Additionally, vehicles certified to California emission
standards (indicated on the underhood Vehicle
Emissions Control Information label) are designed to
operate on California reformulated gasolines. If
California reformulated gasoline is not available
when you refuel, your vehicle can be operated on
non-California fuels. However, even though your
engine will perform adequately on other gasolines,
the performance of the emission control devices and
systems may be adversely affected. Repair of damage
caused by using a fuel that your vehicle was not
designed for may not be covered by your warranty.
Octane recommendation
Your vehicle is designed to use regular gasoline
with an (R+M)/2 octane rating of 87. We do not
recommend gasolines labeled as "regular" in high
altitude areas that are sold with octane ratings of
86 or even less.
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