I believe that most of the intake gasket failures were a result of a crummy batch of gaskets, that were poorly designed. I, and several friends who have/had late 90's GM trucks all had the intake gasket failure. Mine went in winter, and I elected to have it done, because it was unusually arse biting cold outside. The shop that did it, said they do them all the time... and routinely keep the "better" gaskets on hand. That was 6 years ago or more, and no issues. But, I also swapped over to the green, after a thorugh flushing, just to be better safe than sorry. I never add tap water to my rad, strictly distilled water to keep the impurities out. Zero issues to date since then. Before that I had all sorts of water related failures, water pump.. heater hose connections etc etc etc. (all with the factory dex-cool and no tap water added) In those days, I'm not sure what my mileage was, but probably only around 45-50,000 miles. Even now my 97 K1500 only has 85,000 so I thought it was strange that so many failures in the cooling system were happening.
But, in my wifes 01 tahoe, that we had until July of this year, the Dex-cool never caused any problems... or I should say, the tahoe never had any water/cooling related failures.
Maybe the dex-cool is better now, maybe the gaskets are.. maybe there was never an issue with the dex-cool at all. I don't know for sure.. but I just chose to stick with the ol' tried and true green stuff. I'm not worried about something, or somoone drinking it becuase when I change it out I get rid of it correctly. And I keep the system leak free, or fix it right away, and only use distilled water, so corrosion hasn't reared it's ugly head yet.
All in all, I still think that the gaskets used back then were problematic, either by themselves.. or in combo with the dex-cool. The only gelling that I've heard of was when the green was mixed with the DC. So, if anyone switches over, make sure you flush the system very well.
I use the "all makes and models" universal anti-freeze in everything now.
