Ford F-150 Owner's Manual page 409

Maintenance and Specifications
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
3.7L V6/5.0L V8/6.2L V8 engines
"Regular" unleaded gasoline with a pump (R+M)/2 octane rating of 87 is
recommended. 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.
3.5L V6 EcoBoost™ engine
"Regular" unleaded gasoline with a pump (R+M)/2 octane rating of 87 is
recommended. 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. Premium fuel will provide
improved performance and is recommended for severe duty usage such
as trailer tow.
Do not be concerned if your engine
87
sometimes knocks lightly. However,
if it knocks heavily while you are
using fuel with the recommended
(R+M)/2 METHOD
octane rating, see your authorized
dealer to prevent any engine damage.
FFV engine (if equipped)
If your vehicle is flex fuel capable, it 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 exclusively use E85 fuel, it is recommended to fill the fuel tank
with regular unleaded gasoline at each scheduled oil change.
409
2012 F-150 (f12)
Owners Guide, 2nd Printing
USA (fus)