Originally Posted By: SteveSRT8
After lunch with a G team engineer from GM, we now change the coolant only after component failure. I still have an 05 that has never been touched, but normally we put nearly 200k miles on them before something quits and we need to open the system.
Dex is that good.
My mechanic is not a fan of Dex Cool. My mechanic said it does get old and starts to gum up. I have a 2003 Chevy Cavalier that originally had Dex Cool in it from the factory and I do agree with my mechanic's opinion that Dex Cool actually does start to gum up when it gets old. My mechanic recommends to switch a car using Dex Cool over to the Prestone green antifreeze. I have a couple of close friends who have said their mechanics have said the same thing about Dex Cool and those mechanics prefer the tried and true green antifreeze. My personal opinion is completely flush your cooling system properly, refill with the proper antifreeze of your choice and replace the radiator and or coolant overflow caps with brand new caps from the dealer. New caps prevent problems and save engines! I have had radiator caps go bad. I have had caps bought from the local auto parts store not fit properly, so I buy these items from the GM dealer. The GM parts always work properly. Here is a quote from
http://www.sancarlosradiator.com/dex-cool.htm :
"General Motors introduced Dex-Cool to certain lines of vehicles in 1996. Since it was formulated without the addition of silicates (the corrosion inhibitors in green antifreeze) a different corrosion inhibitor strategy was needed. Organic Acid Technology or OAT is the inhibitor part of dex-cool. Unfortunately, the dex-cool is capable a rather nasty breakdown. The residue it leaves behind is very sticky, and likes to find areas in the engine and other areas to "drop out" or "fall out " of solution and stick to the wall surface of engine and radiator. If the residue is in the radiator, hoses, or recovery bottle, it's relatively easy to clean and remove the debris. When the residue is in the heads and block, only a chemical flush will remove this orange mud. In some cases, the orange mud hardens, and seems to expand or push the gasketed surfaces out of position, causing leaks.
2002 Cad
No mileage claim here.
There are some in the industry (including GM) that claim that exposure to "air" causes the Dex-cool to come apart, and that faulty radiator cap design is the culprit. They say that with a faulty cap, the cooling systems allow evaporation, allowing the Dex-cool to destabilize, weaken, and lose it's already marginal protection, and then turn muddy. Others say that poor cylinder head design traps air in pockets, allows condensation and ultimately dilution, resulting in aluminum oxide formation and deposits. Neither of these theories completely explain the whole picture, and these are not a universally shared opinions. If air were the culprit, all Dex-cool systems in every vehicle with a recovery (overflow) container would suffer the same problem. They don't. Reverse flow V-8's would be immune. They aren't.
Most insulting about the whole issue is the GM dealer response to the problem. While the vehicle is still in warranty - turn a blind eye. Yet once the vehicle has gone past the warranty period, the solution is simple: replace the radiator, hoses, intake manifold gaskets and maybe the water pump. I believe it is this response that has spawned the current class action litigation.
There are about 72 brands of coolant on the market today. 95% of all these coolants are manufactured using ethylene glycol and mixed with 50% water when installed in a car or truck. Dex-cool is no exception. The differences between coolant brands comes from the additives that enhance the corrosion protection properties. For years this protection came from silicates, but more recently coolant manufactures have moved away from silicate enhanced coolant, to OAT enhanced coolant. Silicates are discussed more here.
Organic Acid Technology refers to the type of corrosion and rust inhibitors used in the make up of the coolant. OAT formulated coolants provide "background" or reserve protection (works like a vitamin), and as such, tend to react more slowly to situation changes as opposed to the faster acting silicates (works like an aspirin). There are several ingredients that constitute the OAT, including carboxyl, benzoate, borate, triazole, and 2-ethylhexanoic acid. Depending on the brand of coolant, these ingredients may vary. Vehicle manufactures increasingly are moving to OAT coolant, and may have slightly different formulations for different markets. European vehicles have used OAT formulated coolant with an addition of some low level silicates to provide further and faster protection. These are called hybrid inhibitor coolants because they contain both silicates, and OAT formulations. More discussion on coolant, inhibitors, and silicates are discussed here.
Dex-cool manufactures continue to insist that Dex-cool will last 5 years and 150,000 miles, and that the problem is lack of maintenance. In other words, you should be maintaining your maintenance free cooling system."
