Just wanted to share my experiences on a 1986 2wd GL that I have been driving as my shop van for about 6 years now.
The engine was rebuilt just before I bought it and most hoses were replaced at that point.
I have used this van to test the Bar's overtime.
The heater cores are fine and I have not had any leaks in all those years.

OK, in the last year I have exploded numerous hoses while driving.
Some were new at rebuild and others not.
Same outcome......huge hole in them and the hose is extremely soft to the touch both inner and outer.
This has me starting to think that the Bar's Leak HD may contain something that is weakening the hoses.
Possibly the ingredient to keep o rings and seals pliable.

If you are using Bar's...check your hoses.

Hope this helps.

dylan