yes, some leaks can be repaired, it's not unusual for a rad with a good core to need the tanks resoldered after 50 years - hafta ask your local shop about a recore, have them test it and see if it needs one or is worth repairing .... meanwhile leave the cap loose and you'll have less leaking and less further damage .... but I wouldn't blame it on the stop leak, it has its uses and needs to be used properly
Bill
