FORD 2013 Focus v.3 - Manual (Page 171)

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 and a loss of vehicle performance; 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.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives. The use of leaded fuel
is prohibited by law.
Choosing the Right Fuel With a Flex Fuel Vehicle (If Equipped)
Note: If your vehicle is flex fuel capable, it will have a yellow bezel
placed over the fuel fill inlet.
Flex fuel vehicles are designed to use only FUEL ETHANOL
(Ed75-Ed85) fuel blends which contain 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.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives. The use of leaded fuel
is prohibited by law.
170 Fuel and Refueling
2013 Focus (foc)
Owners Guide gf, 3rd Printing, November 2012
USA (fus)