Mazda 2003 Tribute Owner's Manual page 217

Maintenance and Specifications
Octane recommendations
Your vehicle is designed to use
87
"Regular" unleaded gasoline with
pump (R+M)/2 octane rating of 87.
We do not recommend the use of
(R+M)/2 METHOD
gasolines labeled as "Regular" that
are sold with octane ratings of 86 or lower in high altitude areas.
NOTE: 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
Mazda dealer to prevent any engine damage.
Fuel quality
NOTE: 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 (particularly in the United States) because it may cause
these problems to become more pronounced. If the problems persist, see
your authorized Mazda dealer.
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.
Aftermarket products 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
issued 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. In Canada,
look for fuels that display the Auto Makers' Choice logo.
Cleaner air
Mazda endorses the use of reformulated "cleaner-burning" gasolines to
improve air quality.
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