Ford Explorer Owner's Manual page 387

Maintenance and Specifications
Octane recommendations
3.5L V6 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.
2.0L 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.
Fuel quality
If you are experiencing starting, rough idle or hesitation driveability
problems during a cold start, try a different brand of "Regular" unleaded
gasoline.
Do not add aftermarket fuel additive products to your fuel tank. It
should not be necessary to add any aftermarket products to your fuel
tank if you continue to use high quality fuel of the recommended octane
rating. These products have not been approved for your engine and
could cause damage to the fuel system. Repairs to correct the effects of
using an aftermarket product in your fuel may not be covered by your
warranty.
Many of the world's automakers approved the World-Wide Fuel Charter
that recommends gasoline specifications to provide improved
performance and emission control system protection for your vehicle.
Gasolines that meet the World-Wide Fuel Charter should be used when
available. Ask your fuel supplier about gasolines that meet the
World-Wide Fuel Charter.
387
2012 Explorer (exp)
Owners Guide, 1st Printing
USA (fus)