Well if this isn't the most discouraging thread on WTJF.
I've periodically gotten whiffs of coolant that I was usually able to blame on the overflow since I'm almost always driving without windows, but this morning I started up and immediately smelled it, before there would have been any time for air to make it from the engine compartment to my nose. Combined with slowly disappearing coolant...pretty sure my heater core is on borrowed time.
Just read through 6 pages of this and honestly have no idea what to do, other than bypass it and deal with it next winter. I have a wheeling trip in Colorado in August where heat would be nice but losing my coolant would be very much not nice.
Being that this has probably been going on since I bought it in 2020, my seeping heater core could very well outlast one from Performance Radiator, while heating better than a Brassworks, so I'm not even sure replacing it with the current options would even make me trust it any more than I do.