Mazda 6 Service Manual: No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

No.19 excessive shift shock on torque converter clutch (tcc)

No.21 noise occurs at idle when vehicle is stopped in d, s, l ranges, or in r position

Other materials:

Mazda 6 Service Manual: Fuel Requirements
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 st ...

Mazda 6 Service Manual: Operating Tips
Operate the climate control system with the engine running. To prevent the battery from being discharged, do not leave the fan control dial/switch on for a long period of time with the ignition switched ON when the engine is not running. Clear all obstructions such as leaves, snow and i ...