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The use of leaded fuel is prohibited by law and could damage your
vehicle.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives.
Note: Use of any fuel other than those recommended may cause
powertrain damage, a loss of vehicle performance, and repairs may not
be covered under warranty.
Octane recommendations
Your vehicle is designed to use “Regular” unleaded gasoline with a pump
(R+M)/2 octane rating of 87. Some stations offer fuels posted as
“Regular” with an octane rating below 87, particularly in high altitude
areas. Fuels with octane levels below 87 are not recommended.
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.
FFV engines
Your vehicle is designed to use Fuel Ethanol (Ed75–Ed85),“Regular”
unleaded gasoline or any mixture of the two fuels.
Use of other fuels such as Fuel Methanol may cause powertrain
damage, a loss of vehicle performance, and your warranty may be
invalidated.
It is best not to alternate repeatedly between gasoline and E85. If you do
switch fuels, it is recommended that you add as much fuel as
possible—at least half a tank. Do not add less than five gallons (18.9L)
when refueling. You should drive the vehicle immediately after refueling
for at least 5 miles (8 km) to allow the vehicle to adapt to the change in
ethanol concentration.
If you operate your vehicle 50% or more of the time on ethanol, you
should follow a different maintenance schedule. In addition to this, if you
exclusively use E85 fuel, it is also recommended to fill the fuel tank with
regular unleaded gasoline once every 3,000 miles (4,800 km). See
scheduled maintenance information for more information.
Fuel quality
Do not add aftermarket fuel additive products to your fuel tank. It
should not be necessary to add any aftermarket products to your fuel
87
(R+M)/2 METHOD
Maintenance and Specifications
355
2010 Navigator (nav)
Owners Guide (own2002), 1st Printing
USA (fus)