FORD 1998 Expedition - Manual (Page 156)

Do not use supplemental engine oil
additives, oil treatments or engine
treatments. They are unnecessary
and could, under certain
conditions, lead to engine damage
which is not covered by your
warranty.
Changing the engine oil and
filter
Change your engine oil and filter
according to the following mileage
and time requirements, whichever
occurs first:
• Normal Schedule – 8,000 km
(5,000 miles) or six months.
• Severe Duty Schedule - 5,000
km (3,000 miles) or three
months. Severe duty operation
would include extensive idling,
trailer towing, driving in severe
dust and police, taxi or delivery
service.
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,
startup 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.
Maintenance and care
156