FORD 2002 Ranger v.2 - Manual (Page 239)

Change your engine oil according to the appropriate schedule listed in
the scheduled maintenance guide.
Engine Oil Filter Recommendation
Change your engine oil filter according to the appropriate schedule listed
in the scheduled maintenance guide. Ford production and aftermarket
(Motorcraft) oil filters are designed for added engine protection and long
life. If a replacement oil filter is used that does not meet Ford Material
and design specifications, start-up engine noises or knock may be
experienced.
It is recommended you use the appropriate Motorcraft oil filter (or
another brand meeting Ford specifications) for your engine.
BATTERY
Your vehicle is equipped with a
Motorcraft maintenance-free battery
which normally does not require
additional water during its life of
service.
However, for severe usage or in high temperature climates, check the
battery electrolyte level. Refer to the scheduled maintenance guide for
the service interval schedules.
Keep the electrolyte level in each cell up to the “level indicator”.
Do not overfill the battery cells.
If the electrolyte level in the battery is low, you can add plain tap water
to the battery, as long as you do not use hard water (water with a high
mineral or alkali content). If possible, however, try to only fill the battery
cells with distilled water. If the battery needs water often, have the
charging system checked.
Maintenance and Specifications
239