Octane Recommendations; Fuel Quality - Lincoln Town Car 1998 Owner's Manual

Maintenance and care
Repair of damage caused by using
a fuel that your vehicle was not
designed for may not be covered
by your warranty.

Octane recommendations

Your vehicle is designed to use
regular unleaded with an (R+M)/2
87
octane rating of 87. Gasolines
labeled as "Regular" in high
altitude areas that are sold with
octane ratings of 86 or even less
are not recommended.
If there is a "Premium Fuel
91
Recommended" label in the fuel
filler door area, your vehicle is
designed to use "Premium"
(R+M)/2 METHOD
gasoline with an (R+M)/2 octane
rating of 91 or higher for optimum
performance. Gasolines with lower
octane ratings can be used, but
performance and fuel economy
may decrease. Gasolines labeled as
"Premium" in high altitude areas
that are sold with octane ratings of
less than 91 are not recommended.
Do not be concerned if your
vehicle sometimes knocks lightly.
However, if it knocks heavily under
most driving conditions on fuel
with the recommended octane, 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"
161