My 92 4.3 uses 9/16", my 88 Four uses 5/8", my Neighbors 93 uses a15mmAllen.
3/8"
It takes a 17mm Allen wrench to remove the fill plug.
It should be a 3/8" Allen wrench.
The size wrench to remove it should be 15mm.
13mm
What size line wrench for a 2005 freestar
15 millimeter
13mm
On mine it takes 14mm.
A 5/8" socket wrench.
15mm
15mm.