A low level of electrolyte fluid will cause the battery to discharge quickly.

Inspect the electrolyte level at least once a week. If it is low, remove the caps and add enough distilled water to bring the level between the upper and lower level (illustration).
Do not overfill.
Examine the specific gravity of the electrolyte with a hydrometer, especially during cold weather. If it is low, recharge the battery.
Battery Maintenance
Battery RechargingMazda 6 Owners Manual: Trip Computer and INFO Switch (Without Multi-information Display)
The following information can be selected by pressing the INFO switch with the
ignition switched ON.
Distance-to-empty mode
Average fuel economy mode
Current fuel economy mode
Compass mode
If you have any problems with your trip computer, consult an Authorized Mazda
Dealer.
Distanc ...
Mazda 6 Owners Manual: Oil pan
OIL PAN REMOVAL/INSTALLATION
Warning
Hot engine and engine oil can cause severe burns. Turn off the
engine and wait until it and the engine oil have cooled.
1. Disconnect the negative battery cable.
2. Remove the under cover.
3. Drain the engine oil. (See ENGINE OIL REPLACEMENT.)
4. Re ...