Adding to the many issues of Dex-Cool, part of the issue is corrosion of aluminum parts.
Also, this is from personal experience and some experience of other mechanic associates of mine. It seems a magic combo for destruction is to take a GM vehicle with 70-150K on it and flush out the original Dex-Cool. Then put in new Dex-Cool. In my own personal experience more than half a dozen times, right after doing that within a week or two I've had some sort of gasket failure, usually intake or water pump. From what I have gathered it has something to do with acidity or possibly alkalinity.