FORD 2008 Explorer v.3 - Manual (Page 353)

Engine Oil Recommendations
4.0L V6 Engine
Look for this certification
trademark.
Use SAE 5W-30 engine oil
Only use oils “Certified For Gasoline Engines” by the American
Petroleum Institute (API). An oil with this trademark symbol conforms
to the current engine and emission system protection standards and fuel
economy requirements of the International Lubricant Standardization and
Approval Committee (ILSAC), comprised of U.S. and Japanese
automobile manufacturers.
To protect your engine’s warranty use Motorcraft SAE 5W-30 or an
equivalent SAE 5W-30 oil meeting Ford specification WSS-M2C929-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 information.
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 with equivalent performance for your engine application.
Maintenance and Specifications
353