Choosing The Right Fuel; Octane Recommendations; Fuel Quality - Ford 2005 Thunderbird Owner's Manual

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, premium grade fuel generally
contains more metallic additives than regular fuel. We recommend using
regular grade fuel. 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.
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.

Fuel quality

If you are experiencing starting, rough idle or hesitation driveability
problems during a cold start, try a different brand of "Premium"
unleaded 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.
REVIEW COPY
2005 Thunderbird (tbr), Owners Guide (post-2002-fmt) (own2002),
Market: USA_English (fus)
Maintenance and Specifications
91
(R+M)/2 METHOD
199