That old Dex Cool killed my 97 grand prix, radiator, water pump(s) etc... But it was the only thing you could run in it.
I had a '99 S10 ZR2 P/U, bought it new. At 8000 miles, the heater core plugged up. Dex cool turned to brown sludge. Plugged up twice a year after that, the dealer would always acid flush, neutralize, and refill with dex, under warranty. When the warranty ran out, they refused to keep doing the flush unless I paid!
They replaced the water pump and heater core after threats of legal action... I had all the receipts for the flushing that showed the mileage.
When they replaced those components, I forced them to put in good old green coolant (they said "but you'll void the warranty on the parts!"
Drove it for two more years, never had a problem after that.
I've talked to some guys who never had a problem with dex... talked to many more who did. Seemed to be worse with the V6s than the V8s.
Anyway... avoid Dex Cool like the plague!!