FORD 2010 Mustang v.3 - Manual (Page 281)

Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives.
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
Your vehicle is designed to use
“Regular” unleaded gasoline with a
pump (R+M)/2 octane rating of 87.
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.
Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your authorized dealer to
prevent any engine damage.
Octane recommendations (4.6L V8 engine)
Your vehicle will run normally on 87 octane regular fuel without
damaging the engine, but premium fuel with an octane rating of 91
(R+M)/2 or higher is recommended for best overall performance.
For Shelby GT500 octane requirements, see the Shelby GT500
Supplement.
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. Premium unleaded gasoline is not recommended for vehicles
designed to use “Regular” unleaded gasoline because it may cause these
problems to become more pronounced. If the problems persist, see your
authorized dealer.
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
87
(R+M)/2 METHOD
Maintenance and Specifications
281
2010 05+ Mustang (197)
Owners Guide, 3rd Printing
USA (fus)