Fuel Quality - Ford Super Duty Owner's Manual

Fuel and Refueling 189
During the summer season, fuel ethanol may contain a maximum of 85%
denatured ethanol (Ed85) and 15% unleaded gasoline. The fuel ethanol
has a higher octane rating than unleaded regular or premium gasoline
and this allows the design of engines with greater efficiency and power.
Winter blends may contain up to 75% denatured ethanol (Ed75) and up
to 25% unleaded gasoline to enhance cold engine starts. Severely cold
weather may require additional measures for reliable starting. Refer to
the Starting chapter
Ethanol is more chemically active than gasoline. It corrodes some metals
and causes some plastic and rubber components to swell, break down or
become brittle and crack, especially when mixed with gasoline. Special
materials and procedures have been developed for flexible fuel vehicles
and the dispensers used by ethanol fuel providers.

FUEL QUALITY

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.
Choosing the Right Fuel
Use only UNLEADED fuel or UNLEADED fuel blended with a maximum
of 15% ethanol. Do not use fuel ethanol (E85), diesel fuel, fuel-methanol,
leaded fuel or any other fuel because it could damage or impair the
emission control system. The use of leaded fuel is prohibited by law.
Diesel engine (if equipped)
Refer to the diesel supplement for information regarding diesel fuel
recommendations and requirements of your diesel-powered truck.
Choosing the Right Fuel With a Flex Fuel Vehicle (If Equipped)
Note: If your vehicle is FFV capable, it will have a yellow colored fuel cap.
Flex fuel vehicles are designed to use only ethanol fuel blends which
contains 51 to 83% ethanol and UNLEADED FUEL Regular unleaded
gasoline or any mixture of the two fuels.
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 (18.9 liters) when
refueling. You should drive the vehicle immediately after refueling for at least
5 miles (8 kilometers) to allow the vehicle to adapt to the change in ethanol
concentration. If you exclusively use E85 fuel, it is recommended to fill the
fuel tank with regular unleaded gasoline at each scheduled oil change.
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)