Choosing The Right Fuel; Octane Recommendations; Fuel Quality - Ford 1998 Expedition Owner's Manual

Maintenance and care

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 gasolines containing methanol. It can damage critical fuel
systems components.
Vehicles certified to meet California emission standards (indicated on the
underhood Vehicle Emissions Control Information label) are designed to
operate on California cleaner-burning, low-sulfur gasolines. If you have a
California-certified vehicle and California cleaner-burning gasoline is not
available when you refuel, your engine should perform adequately.
However, the performance of the emission control devices and systems
may be adversely affected. In New York and Massachusetts, which have
adopted California's emission standards without requiring the sale of
California cleaner-burning gasoline, repairs to correct the effects of using
non-California fuel may not be covered by the emissions warranty.
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
87
"Regular" unleaded gasoline with an
(R+M)/2 octane rating of 87. We do
not recommend the use of gasolines
(R+M)/2 METHOD
labeled as "Regular" that are sold
with octane ratings of 86 or lower in high altitude areas.
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 "Regular" unleaded
gasoline. "Premium" unleaded gasoline is not recommended (particularly
in the United States) because it may cause these problems to become
more pronounced. If the problems persist, see your dealer or a qualified
service technician.
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