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: Add-On Non-Genuine Parts and Accessories
Non-genuine parts and accessories for Mazda vehicles can be found in stores.
These may fit your vehicle, but they are not approved by Mazda for use with Mazda
vehicles. When you install non-genuine parts or accessories, they could affect your
vehicle's performance or safety systems; the Mazda w ...
Mazda 6 Owners Manual: Foreword
When the customer reports a vehicle malfunction, check the malfunction
indicator lamp (MIL), HOLD indicator light flashing, and PCM memory for
diagnostic trouble code (DTC), then diagnose the malfunction according to
following flowchart.
- If the DTC exists, diagnose the applicable ...