Ford Taurus 2011 Owner's Manual page 350

Maintenance and Specifications
Octane recommendations
3.5L V6 engine
Your vehicle will run normally on
87 octane regular fuel. Premium fuel
will provide improved performance.
3.5L V6 SHO engine
Your vehicle is designed to run on regular fuel with an octane rating of
87 or higher. For best overall performance, premium fuel with an octane
rating of 91 or higher is recommended. The performance gained by using
premium fuel will be most noticeable in hot weather or in severe duty
applications such as towing a trailer.
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 for either engine. Do not be concerned if your
engine sometimes knocks lightly. However, if it knocks heavily while you
are using fuel with the recommended 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 unleaded gasoline.
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
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.
350
2011 Taurus
Owners Guide, 3rd Printing
USA (fus)
87
(R+M)/2 METHOD