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: Climate control unit removal
1. Disconnect the negative battery cable.
2. Disconnect the air mix and airflow mode wires from each wire clamp and
link. (Manual air conditioner)
3. Remove the center panel. (See CENTER PANEL MODULE REMOVAL/INSTALLATION.)
4. Remove the screws and climate control unit. (Full-auto air conditione ...
Mazda 6 Owners Manual: Engine coolant temperature (ect) sensor removal/installation
Warning
When the engine is hot, it can badly burn. Turn off the engine and
wait until it is cool before removing the ECT sensor.
1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.)
2. Disconnect the ECT sensor connector.
3. Remove the ECT sensor.
4. Install in the reve ...