Yes you can but be sure to release the pressure first. The filter should be changed once a year and is typically located on the left (drivers) side behind the sliding door in the rail system. Kind of hard to find but not hard to replace.
According to the 2005 Ford Freestar Owner Guide ( Motorcraft FL-400-S ) engine oil filter
When it gets dirty.
For the 2004 Ford Freestar : 3.9 and 4.2 liter V6 engines : ( Motorcraft FL-400-S engine oil filter ) according to one of Fords websites
It will hold 5 quarts exactly with a filter change.
2007 ford freestar
Ford Freestar was created in 2004.
According to the 2007 Ford Freestar Owner Guide : For the 3.9 and 4.2 liter V6 engines : With engine oil filter change : ( 5 U.S. quarts )
About $10 See "Related Questions" below for more
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Oil filter is located under lowest end of the serpentine belt, passenger side of the vehicle, between the lower frame angle.
( 26 U.S. gallons ) for a 2004 Ford Freestar