DexCool - VERY IMPORTANT

[sparg93]

Some of you may already know this, but I'm sure there are a few folks that can benefit from this little piece of knowledge.

DexCool, used in GM vehicles since '96 (not sure if new vehicles come with it) have contained DexCool antifreeze. Over time DexCool turns acidic and can even form a rusty orange sludge within your cooling system when exposed to air.

Car owners have reported damage to multiple components (gaskets, hoses, etc) and fairly expensive repair bills (head gasket replacement = $1500+ for Tahoes). However, when serviced correctly and consistently, DexCool is an excellent antifreeze.

It is HIGHLY recommended that every few years you COMPLETELY drain your system of DexCool...some even recommending that you have your system chemically cleaned; especially if you already have orange sludge showing up on your radiator cap.

From my research, it appears when air touches DexCool, the antifreeze starts to have issues. It is recommended that you should always (and you should do this anyway) keep coolant in your reservoir b/c once the tank drains, the coolant will be exposed to air. On our trucks, we have huge reservoirs - there is no issue I'm aware of by filling it to "Hot" when your truck is Cold...just added insurance.

Some quick articles I found today:
http://www.sancarlosradiator.com/dex-cool.htm
http://consumeraffairs.com/news04/2006/08/gm_dexcool.html

Comment from a Tahoe owner:
http://www.consumeraffairs.com/automotive/gm_dexcool.html

Also, DO NOT MIX ANTIFREEZES. If you mix orange and green, you WILL have issues as the green antifreeze will break down DexCool. You also don't need to convert your car to another form of antifreeze, DexCool works great....just remember to clean it fairly regularly and keep your system free from air.

GM recommends one drain every 5yr (IIRC)...but from what I have read, you should do it sooner then that.

I hope this helps!!

 

[HankHill]

I have a 1999 S10 2.2. Bought it brand-new; it now has 180K. It has DEXCOOL. Changed the thermostat once, never drained it or done any maintenance to the cooling system otherwise. Original water pump, hoses, rad, etc. Runs like a champ. Drove it today. YMMV....

 

[96ProCompTahoe]

not had any problems with it in the tahoe, but did in my 95 sonoma, more on the previous owner than the truck itself. honestly not sure what/how they did it but it all got flushed and swapped to green when i replaced the head gasket.

its really not as bad as all those hyped up articles about it as long as you maintain your vehicle. also have heard if you have a bad rad. cap it can cause it to gunk up from the air.

 

[sparg93]

Agreed - it all depends on how much air you get in the system. I had a problem with my old Grand Prix and it really got gunked up.

Like I said, DexCool is great antifreeze. In our vette we've had the same antifreeze in it since '96 and never had an issue.

Maybe the message came off too strong in my original post...my intention was more to educate people b/c you can definitely have problems if this stuff starts to turn sour. And for how easy it is to drain and refill, it's worth your piece of mind...especially if you start seeing orange crud around your pressure cap.

HankHill - what is YMMV?

 

[puckhead]

What about that antifreeze at Wally World that says you can add to any color? Is that any good?

 

[SunlitComet]

To late for me I got my Tahoe with a dirty system and just after cleaning the system out with a little remaining and some high gauge readings during the cleaning process I had an internal engine failure. Will be torn down next week hopefully with lots of pics.

 

[nimrodcs]

Had dexcool problems with a 2001 blazer with the 4.3L vortec. They used plastic intake manifold gaskets in the 3.4L and 4.3L engines. Dexcool contains a chemical closely related to a plasticiser, which will start to break down the IMGs after about 90,000 miles. This will lead to a number of problems. With mine, it was random cylinder misfires due to the coolant leaking into and corroding 3 exhaust valves shut. After changing the IMG's twice and a complete valve job on both heads, plus switching to the glycol (green) coolant, it ran like a top. Then, I sold that problematic ************* and got a Tahoe! My wife had an Olds Alero with the 3.4L and had the same problem.

I do believe they used metal and rubber IMG's in the 2.2L's and 5.7L's, thats why there weren't many problems on the L4's and V8's.

Do not mix Dexcool with any other coolant! It will sludge up inside your system and cause a nasty mess. I know from experience......