Octane Recommendations; Fuel Quality - Lincoln LS 2000 Owner's Manual

Maintenance and care
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
91
"Premium" unleaded gasoline with
an (R+M)/2 octane rating of 91 or
higher for optimum performance.
(R+M)/2 METHOD
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.
Many of the world's automakers issued 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.
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