Hoping this one dont get out of control.
See.......its like this.
DexC (Organic Acid Technology) just dont play nice with the other coolants (Inorganic Additive Technology) that may move into DexC's neighborhood at some point in time, especially when it was the first one in the neighborhood to start with. This includes the clay tablets that GM added at the factory.
In the simplest of terms......it just hates everyone else (cept distilled water).
Now, when the neighborhood is an LT1, it really gets piSSed when oxygen moves in. So thats why I always recommend (after a flush and fill) that folks bleed it, bleed it, then bleed it again. Then in the morning bleed it again.
The problems seem to start when owners unknowingly dump in IAT coolants to top off the system thinking all will be fine. Sure they mix fine for a while but then something happens to them when they are in this killer environment together, over time. Nobody seems to know exactly what goes down, but it gets really ugly.
Of course neglect is a big problem too, by not keeping a factory DexC system properly filled, maintained and flushed periodically. Lets face it folks 5 year coolant was a sales lie from the get go, period.
Also, letting the tank level get well under "cold fill" really fires up DexC's temper.
So, I have learned to thoroughly flush the system every two years and always use DexC with distilled water. Then do the air bleed.
No probs.