Ford Mustang Owner's Manual page 268

Ford Gas Stabilizer should be added whenever
actual or expected storage periods exceed 60
days. Follow the instructions on the label. The
vehicle should then be operated at idle speed to
circulate the additive throughout the fuel system.
Cooling system
Protect against freezing temperatures.
Battery
Check and recharge as necessary.
Keep connections clean and covered with a
light coat of grease.
If storing your vehicle for more than 30 days
without recharging the battery, it may be
advisable to disconnect the battery cables to
ensure battery charge is maintained for quick
starting.
NOTE: If battery cables are disconnected, it
will be necessary to reset memory
features.
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