In article , Speedy Jim wrote:

Inject a product like "Stop Leak" into the system?

NO!!!

A corrosion-inhibitor mixed with the boiler water *might*
help, but only if the corrosion is from within and not
on the outside. (I'm not a corrosion engineer.)

Be very, very careful. Automotive coolant should never be used in a hydronic
system.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.