Turn the auxiliary key toward the front to lock, toward the back to unlock.
To lock
All doors lock automatically when the driver's door is locked using the auxiliary key.
To unlock
The driver’s door unlocks when the auxiliary key is turned briefly to the unlock position and then immediately returned to the center position.
All doors unlock when the driver's door is unlocked and the auxiliary key is held in the unlock position for one second or longer.

Door Locks
Locking, Unlocking with Request Switch, Door Handle (With the advanced keyless
function)Mazda 6 Owners Manual: Underbody Maintenance
Road chemicals and salt used for ice and snow removal and solvents used for dust
control may collect on the underbody. If not removed, they will speed up rusting
and deterioration of such underbody parts as fuel lines, frame, floor pan, and exhaust
system, even though these parts may be coated ...
Mazda 6 Owners Manual: Oil cooler
LF, L3
1. Remove the under cover.
2. Drain the engine coolant. (See ENGINE COOLANT REPLACEMENT.)
3. Remove the oil filter cover, and drain the engine oil into a container.
(See OIL FILTER REPLACEMENT.)
4. Remove in the order indicated in the table.
5. Use a clean rag to wipe off the m ...