use phosphoric acid first and/or a good metal prep to neutralize the contamination in there .... I wouldn't use filler over POR15, I don't think it would stick to the gloss very well, better on the treated bare metal
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
