As a rule, should filler (Bondo) go on bare metal only? What if you wanted to rust proof a small section (Por 15) and fill over it a bit. Taboo ? or OK? Im thinking of the small holes at the lower corner of where my windshield sits. Thanks Ken 1979 Scirocco 16V - Almost done 81 Deisel P/U - Rescued from neglegent PO VORTEX: "Indiana Red"