So yea...I know we're supposed to use Dexcool coolant in our radiators...but...i had it in the shop because my intake gasket basically corroded away....he said it was the dexcool. he said "I honestly believe that GM made dexcool really corrosive so that GM can insure repairs down the road...he refilled it with normal green stuff...but it looks really strong..i was gonna flush it out becuase i have a flush kit...i just dont know what i should refill it with...green...or dexcool....

 

there is stuff out there that is green but it can be used in engines that require dexcool. basically its a universal coolant. thats prolly waht your mechanic filled it with.

and yes dexcool does suck

 

A quick search would have yielded a discussion on dexcool. Dexcool is actually a much more effective cooling medium for todays engines than ethylene glycol (green) due to the fact that it does not wet the surface. As far as dexcool eating the gasket, false. GM is well known for poor intake manifold gasket material choice and design. Practically all dexcool problems are from either lack of maintenance (not keeping the overflow tank full) or from a cooling system integrity failure (blown gasket, failed radiator cap, etc). Both of which allow air to enter the system. Once air is in a dexcool based system, the fact that dexcool does not wet and keep anti-corrosion inhibitors on the passages of the cooling system means that these areas are unprotected. If allowed to continue without protection, corrosion sets in and it's a down hill slide from there.

And the fact that less than 0.01% of all vehicles produced with dexcool has problems means that it sucks... Yeah ok...

Now onto the question at hand. Because of the price of dexcool compared to many of the other extended life antifreeze variants out there, I would have to recommend the alternatives. They work just as well and last just as long as dexcool. I have used Prestone's 'All Makes, All Models' Extended Life antifreeze in all of my dexcool equiped vehicles as well as my families without issue.

You will want to buy several gallons of distilled water for your flush. I used 6 or so when I flushed the cooling system on my Bravada a month or so ago. I flushed with normal tap water for quite some time, and filled with water. Then ran it with the water in and took everything apart again and flushed it out some more. Then I drained the system as completely as I could and flushed it with distilled water and drained it again. Then filled with 6qts of prestone yellow coolant and topped off with distilled water. Filled the over flow bottle with 50/50 mix of prestone yellow and distilled water. Went through several temp cycles to make sure all of the air was worked out and it's good to go with a new t-stat and radiator cap.