Vehicles with catalytic converters or oxygen sensors must use ONLY UNLEADED FUEL, which will reduce exhaust emissions and keep spark plug fouling to a minimum.
This vehicle will perform best with fuel listed in the table.

* U.S. federal law requires that octane ratings be posted on gasoline station pumps.
Fuel with a rating lower than 87 octane (91 RON) will negatively affect the emission control system performance and could also cause engine knocking and serious engine damage.
CAUTION
Leaded fuel is harmful to the catalytic converter and oxygen sensors and will lead to deterioration of the emission control system and or failures.
Gasoline blended with oxygenates such as alcohol or ether compounds are generally referred to as oxygenated fuels. The common gasoline blend that can be used with your vehicle is ethanol blended at no more than 10 %. Gasoline containing alcohol, such as ethanol or methanol, may be marketed under the name "Gasohol".
Vehicle damage and drivability problems resulting from the use of the following may not be covered by the warranty.
Emission Control SystemMazda 6 Owners Manual: Transmitter battery replacement
1. Insert a small screwdriver into the slot and gently pry open the
transmitter.
2. Press the portion of the battery indicated by A and remove the battery.
3. Install a new battery (CR2025) into the front portion of the holder with
the positive pole (+) facing up. Press on the B portion of ...
Mazda 6 Owners Manual: Fuel-Filler Lid and Cap
WARNING
When removing the fuel-filler cap, loosen the cap slightly and wait for
any hissing to stop, then remove it: Fuel spray is dangerous. Fuel can burn
skin and eyes and cause illness if ingested. Fuel spray is released when there is
pressure in the fuel tank and the fuel-filler cap is re ...