Page 281 of 312

FUEL FILTER
For fuel filter replacement, see your authorized dealer. Refer to
scheduled maintenance informationfor the appropriate intervals for
changing the fuel filter.
Replace the fuel filter with an authorized Motorcraft part. The
customer warranty may be void for any damage to the fuel system
if an authorized Motorcraft fuel filter is not used.
WHAT YOU SHOULD KNOW ABOUT AUTOMOTIVE FUELS
Important safety precautions
Do not overfill the fuel tank. The pressure in an overfilled tank
may cause leakage and lead to fuel spray and fire.
The fuel system may be under pressure. If the fuel filler cap is
venting vapor or if you hear a hissing sound, wait until it stops
before completely removing the fuel filler cap. Otherwise, fuel may
spray out and injure you or others.
If you do not use the proper fuel filler cap, excessive vacuum in
the fuel tank may damage the fuel system or cause the fuel cap
to disengage in a collision, which may result in possible personal injury.
Automotive fuels can cause serious injury or death if misused or
mishandled.
Gasoline may contain benzene, which is a cancer-causing agent.
Observe the following guidelines when handling automotive fuel:
•Extinguish all smoking materials
and any open flames before
refueling your vehicle.
•Always turn off the vehicle before
refueling.
2007 Navigator(nav)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
281
Page 284 of 312

If you must replace the fuel filler cap, replace it with a fuel filler
cap that is designed for your vehicle. The customer warranty may
be void for any damage to the fuel tank or fuel system if the
correct genuine Ford or Motorcraft fuel filler cap is not used.
The fuel system may be under pressure. If the fuel filler cap is
venting vapor or if you hear a hissing sound, wait until it stops
before completely removing the fuel filler cap. Otherwise, fuel may
spray out and injure you or others.
If you do not use the proper fuel filler cap, excessive vacuum in
the fuel tank may damage the fuel system or cause the fuel cap
to disengage in a collision, which may result in possible personal injury.
Choosing the right fuel
Use only UNLEADED fuel or UNLEADED fuel blended with a maximum
of 10% ethanol. Your vehicle was not designed to run on E85 fuels that
are blended with a maximum of 85% ethanol. The use of leaded fuel is
prohibited by law and could damage your vehicle. Do not use fuel
containing methanol. It can damage critical fuel system components.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives. Studies indicate that
these additives can cause your vehicle’s emission control system to
deteriorate more rapidly. In Canada, premium grade fuel generally
contains more metallic additives than regular grade fuel. We recommend
using regular grade fuel. In Canada, many fuels contain metallic
additives, but fuels free of such additives may be available; check with
your local fuel dealer.
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
“Regular” unleaded gasoline with
pump (R+M)/2 octane rating of 87.
We do not recommend the use of
gasolines labeled as “Regular” that
are sold with octane ratings of 86 or lower in high altitude areas.
87(R+M)/2 METHOD
2007 Navigator(nav)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
284
Page 288 of 312

•You may want to turn off the speed control in hilly terrain if
unnecessary shifting between the top gears occurs. Unnecessary
shifting of this type could result in reduced fuel economy.
•Warming up a vehicle on cold mornings is not required and may
reduce fuel economy.
•Resting your foot on the brake pedal while driving may reduce fuel
economy.
•Combine errands and minimize stop-and-go driving.
Maintenance
•Keep tires properly inflated and use only recommended size.
•Operating a vehicle with the wheels out of alignment will reduce fuel
economy.
•Use recommended engine oil. Refer toMaintenance product
specifications and capacitiesin this chapter.
•Perform all regularly scheduled maintenance items. Follow the
recommended maintenance schedule and owner maintenance checks
found inscheduled maintenance information.
Conditions
•Heavily loading a vehicle or towing a trailer may reduce fuel economy
at any speed.
•Carrying unnecessary weight may reduce fuel economy (as much as
1 mpg [0.4 km/L] is lost for every 400 lb [180 kg] of weight carried).
•Adding certain accessories to your vehicle (for example bug
deflectors, rollbars/light bars, running boards, ski/luggage racks) may
reduce fuel economy.
•Using fuel blended with alcohol may lower fuel economy.
•Fuel economy may decrease with lower temperatures during the first
8–10 miles (12–16 km) of driving.
•Driving on flat terrain offers improved fuel economy as compared to
driving on hilly terrain.
•Transmissions give their best fuel economy when operated in the top
cruise gear and with steady pressure on the gas pedal.
•Four-wheel-drive operation (if equipped) is less fuel efficient than
two-wheel-drive operation.
•Close windows for high speed driving.
2007 Navigator(nav)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
288