Ford 1997 Mark VIII, Owner'S Manual

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246
Octane recommendation
Your vehicle is designed to use premium gasoline
for optimum performance with an (R+M)/2 octane
rating of 91 or higher. Gasolines with lower octane
ratings can be used, but performance and fuel
economy may decrease. We do not recommend
gasolines labeled as “premium” in high altitude
areas that are sold with octane ratings less than 91.
Typical octane rating label
Do not be concerned if your vehicle sometimes
knocks lightly. However, if it knocks heavily under
most driving conditions on the recommended
octane fuel, see your dealer or a qualified service
technician to prevent any engine damage.
Fuel quality
If you are experiencing starting, rough idle or
hesitation problems try a different brand of fuel. If
the condition persists, see your dealer or a qualified
service technician.
The American Automobile Manufacturers
Association (AAMA) issued a gasoline specification
to provide information on high quality fuels that
optimize the performance of your vehicle. We
recommend the use of gasolines that meet the
AAMA specification if they are available.
It should not be necessary to add any aftermarket
products to your fuel tank if you continue to use a
high-quality fuel.
File:11fnmc8.ex
Update:Thu Jun 20 14:28:32 1996