According to the 1999 Mercury Mountaineer Owner Guide :
For the 4.0 liter SOHC , V6 engine and the 5.0 liter V8 engine :
With engine oil filter change :
( 5.0 U.S. quarts )
4.5 quarts with oil
5 quarts, 5w30
4 quarts
5
( 5 quarts ) with engine oil filter change
without oil filter 3.7 quarts with oil filter 4.2 quarts
About 4 quarts.
( 5 quarts ) with engine oil filter change
Six
4.3
( 5 quarts ) with engine oil filter change
5 quarts.