The rear armrest in the center of the rear seatback can be used (no occupant in the center seat) or placed upright.

WARNING
Never put your hands and fingers around the moving parts of the seat and armrest:
Putting your hands and fingers around the moving parts of the seat and armrest is dangerous as they could get injured.
Split Folding
Head RestraintsMazda 6 Owners Manual: Oil cooler flushing
Note
The contaminated cooler line (oil pipes and hoses) and auxiliary
cooler must be flushed completely when ATX is overhauled or replaced.
1. Remove the two oil cooler line hoses and apply air pressure of 196 kPa
{2.0 kgf/cm2, 28 psi} from the return hose (pipe) side.
Caution
Power ...
Mazda 6 Owners Manual: Front buckle removal/installation
1. Perform the following procedure for vehicles with seat belt warning.
(1) Disconnect the negative battery cable.
(2) Remove the front seat.
(3) Disconnect the buckle switch connector.
2. Perform the following procedure for vehicles without seat belt warning.
(1) Remove the console.
...