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: Fuel Gauge (Without Multiinformation Display)
The fuel gauge shows approximately how much fuel is remaining in the tank when
the ignition is switched ON. We recommend keeping the tank over 1/4 full.
If the low fuel warning light illuminates or the fuel level is very low, refuel
as soon as possible.
Refer to Warning Lights.
NOTE
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Mazda 6 Owners Manual: Wheel alignment pre-inspection
1. Inspect the tire inflation, and adjust to the recommended pressure as
necessary.
2. Inspect the front wheel bearing play and correct it if necessary. (See
Wheel Bearing Play Inspection.)
3. Inspect the wheel and tire runouts. (See SUSPENSION.)
4. Inspect the ball joints and steering linkag ...