If you use dexcool and don't change the coolant annually in that year, it will destroy the intake gaskets.
Our 05 had Dexcool in it until about 250000 miles (and it was never changed), when I had to change the water pump. I replaced the water pump, flushed the system with water, and put in O'Reilly brand 50/50 Dexcool compatible coolant, and got it back on the road. Never have had to replace intake gaskets. Tahoe now has 310000 and still going strong.