FORD 2005 Mustang v.3 - Manual (Page 215)

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 authorized dealer to
prevent any engine damage.
Fuel quality
If you are experiencing starting, rough idle or hesitation driveability
problems, try a different brand of unleaded gasoline. “Premium”
unleaded gasoline is not recommended for vehicles designed to use
“Regular” unleaded gasoline because it may cause these problems to
become more pronounced. If the problems persist, see your authorized
dealer.
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
performance and emission control system protection for your vehicle.
Gasolines that meet the World-wide Fuel Charter should be used when
available. Ask your fuel supplier about gasolines that meet the
World-wide Fuel Charter.
Cleaner air
Ford endorses the use of reformulated “cleaner-burning” gasolines to
improve air quality.
Running out of fuel
Avoid running out of fuel because this situation may have an adverse
effect on powertrain components.
If you have run out of fuel:
• You may need to cycle the ignition from OFF to ON several times after
refueling, to allow the fuel system to pump the fuel from the tank to
the engine.
• Your Service engine soon indicator may come on. For more
information on the Service engine soon indicator, refer to the
Instrument Cluster chapter.
Fuel Filter
For fuel filter replacement, see your authorized dealer. Refer to
scheduled maintenance information for the appropriate intervals for
changing the fuel filter.
2005 05+ Mustang (197)
Owners Guide (post-2002-fmt)
USA (fus)
Maintenance and Specifications
215