a word on POR-15..  its good (expensive) stuff, but its not a cureall.   if
you dont properly prep the surface, or redo the seams, or stop the rust at its
orgin, POR-15 is useless..just a band aid.   POR-15 will not stop rust. its
just a epoxy based coating.  its a tough coating tho..  only reccomended for
underbody applications, or suspension parts, or other parts that dont get
subjected to UV rays or need to be topcoated.
in otherwords, its fine to use in your wheelwells etc, but i wouldnt use it
on the outside of your van where it needs to be topcoated..

chris