When I had to replace the waterpump in my 05 GTO (2017) I drained and flushed the Dex Cool out, and switched to the universal extended life green type that is compatible with any coolant. Going on 4 years now with no issues.
Considering the block and heads are aluminum in an LS2 there was definite scale and sediment when I flushed it. The new coolant is 5 years 100,000 miles life expectancy. The Dex Cool was 12 years old, so it was well beyond it's life expectancy. The mileage was within, but the time was long expired.
I never was a fan of the Dex Cool, it always looks thickened, even when it's not been contaminated with any other antifreeze. I've got old cars that have sat for decades with the same green antifreeze in them that look better than the Dex Cool cars.
I also have a 99 3.1 GP that I swapped from Dex Cool to green antifreeze, still has the original radiator. I also swapped my 2008 Vibe from Dex Cool to green when the cooling fan motor went to hell, and the fan chewed up the radiator, and needed replacement. It has over 310,000 miles on it, functioning just fine.
