FORD 2004 Explorer v.2 - Manual (Page 233)

Motorcraft SAE 5W-30 or an equivalent 5W-30 oil meeting Ford
specification WSS-M2C205–A.
Do not use supplemental engine oil additives, cleaners or other engine
treatments. They are unnecessary and could lead to engine damage that
is not covered by Ford warranty.
Change your engine oil 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 application.
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.
If your battery has a cover/shield, make sure it is reinstalled
after the battery has been cleaned or replaced.
2004 Explorer (exp)
Owners Guide (post-2002-fmt)
USA English (fus)
Maintenance and Specifications
233