FORD 2012 F-550 v.1 - Manual (Page 397)

Filling the tank
The advertised fuel capacity of the fuel tank on your vehicle is equal to
the rated refill capacity of the fuel tank as listed in the Maintenance
product specifications and capacities section of this chapter.
The advertised capacity is the amount of the indicated capacity and the
empty reserve combined. Indicated capacity is the difference in the
amount of fuel in a full tank and a tank when the fuel gauge indicates
empty. Empty reserve is the small amount of fuel remaining in the fuel
tank after the fuel gauge indicates empty.
The amount of usable fuel in the empty reserve varies and should
not be relied upon to increase driving range. When refueling your
vehicle after the fuel gauge indicates empty, you might not be
able to refuel the full amount of the advertised capacity of the
fuel tank due to the empty reserve still present in the tank.
For consistent results when filling the fuel tank:
• Turn the engine/ignition switch to the off position prior to refueling,
an error in the reading will result if the engine is left running.
• Use the same filling rate setting (low — medium — high) each time
the tank is filled.
• Allow no more than two automatic click-offs when filling.
• Always use fuel with the recommended octane rating.
• Use a known quality gasoline, preferably a national brand.
• Have the vehicle loading and distribution the same every time.
Your results will be most accurate if your filling method is consistent.
Calculating fuel economy
1. Fill the fuel tank completely and record the initial odometer reading
(in miles or kilometers).
2. Each time you fill the tank, record the amount of fuel added (in
gallons or liters).
3. After at least three to five tank fill-ups, fill the fuel tank and record
the current odometer reading.
4. Subtract your initial odometer reading from the current odometer
reading.
5. Follow one of the simple calculations in order to determine fuel
economy:
Calculation 1: Divide total miles traveled by total gallons used.
Maintenance and Specifications
397
2012 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)