Ford 1997 Aerostar Manual page 248

Battery
Your vehicle may have a Motorcraft
maintenance-free battery. The Motorcraft
maintenance-free battery does not require
additional water during its life of service. The
vents are part of the cover and cannot be
removed. For longer, trouble-free operation, keep
the top of the battery clean and dry. Also, make
certain the battery cables are tightly fastened to
the battery terminals.
If you see any corrosion on the battery cables or
terminals, remove the cables from the terminal
and clean them both with a wire brush. You can
neutralize the acid with a solution of baking
soda and water. Reinstall the cables when you
are done cleaning them, and apply a small
quantity of grease to the top of each battery
terminal to help prevent corrosion.
Battery replacement
If your original equipment battery requires
replacement (under warranty), it may in some
cases be replaced by a Motorcraft
low-maintenance battery. The low-maintenance
battery has removable vent caps for checking the
electrolyte level and for adding water, if needed.
Check your battery's electrolyte level, at least
every 12 months or 12,000 miles (20,000 km), in
temperatures up to 90˚F (32˚C) and more often
in temperatures above 90˚F (32˚C). Keep the
electrolyte in each cell up to the "level"
indicator. Do not overfill the battery cell.
If the electrolyte level in your battery gets low,
you can add plain tap water to the battery, as
long as you don't use hard water, or water with
a high mineral or alkali content. If possible,
however, try to only fill the battery cell with
distilled water. If the battery needs water often,
have the charging system checked.
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