I was given a Buick Le Sabre for free from my friend, he had slid into a tree in my yard and made a small leak in his radiator. He put the gold Bar's Leak in. It stopped the leak, but it's always had cooling issues since.
I replaced the thermostat and water pump, both had the gold [censored] stuck to them and needed replaced, I took off every hose, cleaned and reattached the hoses. Removed the over flow and scrubbed it with a tooth brush. Cleaned the temp sensor. Ran garden hose through the cooling system and forced more out.
If I were to use it again, I would run it long enough that the leak stops and then flush my cooling system with water until I didnt see flakes.
I would flush the system before putting in the new radiator, then with the radiator out, run a hose and circulate more water into it. Make sure to use distilled water when refilling the new radiator.