welcome to the garage JDL, you found the place for info about the ol rig soldering works well as a filler for pinholes ... as in "leading", but like Scott sez, not a real rust repair option, time to get an inexpensive MIG
"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