UPDATE: Anyone ever use copper seal powder for radiators? Seems to have worked. I flushed the system yet again and re serviced with the copper seal and royal purple radiator coolant. Also, took everyone's advise and checked the radiator cap and sure enough there was a small tear in the upper seal (seems there were three seals in the cap), so had to change. Seems to have done the trick!!! Thanks for everyone's input, saved a bunch of money and labor time!
