Because of daily expansion and contraction of the block any epoxy fix would be in the temporary repair area.
Over 30 years I have used the Bar's brand for coolant leaks, probably only 5 or 6 times though.
Not once have I ever had a problem with heater core or rad clogging because of the Bar's.
I have fixed cars that people used stop leak products on that did have clogged rads and cores, but this was NOT caused by the stop leak product.
The cause of the clogging, and the leak, was because cooling system was corroding from the inside out, lol, they never changed coolant or flushed the system, so clogging was already well under way before stop leak was used.
This is just my personal opinion and observation.
I think the "myth" of the clogging is from the general idea that something that clogs a leak must then clog any smaller passages, which is true but heater cores and rads do not have small passages, they are large in comparison to a leak passage in the system.
The "myth" is repeated often and reinforced by mechanics or "wanna be" mechanics because it reinforces their roll as a service provider.
Bar's does NOT fix the leak, it stops the leak until it can be repaired properly.
Last edited by RonR; 12-13-2012 at 11:46 AM.