I've sat and read all the knowledgeable sources on Dexcool, mostly lay people and mechanics with high school educations, while others believed the theories from various folks.
Especially amusing was those in the late 90s or early 200x years who swore how they escaped the Dexcool plague by putting in the Prestone Mixes with All Brands antifreeze. The SDS on those showed the same ingredients as Dexcool. LOL.
The variations on Dexcool from some of the other manufacturers using similar ingredients became confusing, especially when recited by some of the folks with an agenda.
Early on in Dexcool two things happened. Ford was using it and found that air trapped in the system by the design of the filler neck on a truck model caused the Dexcool to deteriorate. This was early in the Dexcool introduction. By 1998/99 to my thinking when people started blaming DC for gasket failures and upper
intake manifold failures along with Dexcool had been modified for the antioxidation additive they used.
Other deterioration came from vehicles not heated thoroughly so that the coolant all got run very hot in the cycles through the engine. The claim I read was that the natural bacteria present deteriorated the antioxidant GM was using in those vehicles causing early problems before the 5-year, 100K mile lifetime. In engines run for short periods those contaminants didn't get sterilized.
Apparently GM made some minor change to formulas later and extended the total miles the coolant should serve.
Having had a 2005 Cobalt, 2015 Cruze, and 2014 Malibu all with Dexcool, I can say I've not had a single gasket failure in them due to Dexcool. Indeed, I realized my Malibu was creeping up on 8 years and I have started replacing the Dexcool. It tested perfectly good, BTW. Amazing quality.
I believe I understand what BGFM said and I believe you'd be better served keeping Dexcool (or the Prestone Mixes with All Coolant Types, same thing) in the engine and system. I'd have more concern about putting a concoction in the radiator and engine without the ingredients GM and its research partners (Prestone?) developed through the years.
The ingredients in Dexcool have been fully researched, restudied, and improved through the 20+ years. Your opinion may vary, but please don't give me a bunch of $% anecdotal evidence from folks, magazine writers, blog posters, or mechanics, with no background in chemistry and/or physics involved as if it were scientific evidence. I read a lot of SDS to find the materials in the various products. I read a lot of scientifically-based papers on the subject as it was studied through the decades.
I'll say the same for the Dexos specification system GM developed for oils, as well.
