From searching the archives, I've seen responses to mixing the two different coolants range from it will cause various disastrous results to not sure. I came across this:

"7. Mixing a 'green' coolant with DEX-COOL reduces the batch's change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed."

From GM and Texaco themselves:

http://www.imcool.com/articles/antif...l-macs2001.htm

Since I purchased my Blazer used, I have no idea what anyone has or has had in the cooling system, so I may as well just top it off with the green stuff, and deal with what to do with the entire system this Summer.

Question is, once I do flush the system, is there any real advantage to the DEX-COOL other than it supposedly lasting five years ?

 

That is a good article. If only everyone were to be made aware of all of the required maintenance for a DEX-COOL system instead of just waiting for a problem and then bashing it.

I would not just use green coolant, unless you really know for sure that you are going to be giving it a good flush/fill this summer. I do not even have any green antifreeze in my garage anymore because nothing I own uses it. I keep 2 50/50 bottles of Prestone Dex-Cool compliant anti-freeze and distilled water on hand.

The only other advantage of DEX-COOL other than the extended life is the lower environmental impact of the fluid itself. It is much more environmentally friendly than the Propylene Glycol (green) antifreeze.

Here is another article that explains the differences between Red and Green:
Antifreeze: Red or Green?

Inorder to fully make the switch to Green, you really must have the system ENTIRELY flushed and should also do a chemical flush of the system to make sure that it is clean. I'll be doing just a water flush this summer and then refilling with a 50/50 mix of distilled water and Dex-Cool compliant antifreeze.

 

I have a 98 Blazer, 75k, and it still has Dex-Cool in it. I had emptied, flushed, and filled the cooling system at 5 years, as required. Up til a month ago, I had no problems. Then I started seeing red fluid on the garage floor. Turned out it was actually orange Dex-cool. The leak is coming off the back of the engine, I suspect from the intake manifold(s). The leak dropped the level in the overflow bottle, and allowed air to get into the cooling system. Dex-cool responded by turning corrosive and started rusting the engine. In that short time I got a rust deposit in the overflow bottle. I plugged the leak with Bar's Leaks, and have to decide what to do next.

Tentatively I plan to flush the system and switch to green anti-freeze. I don't think anti-freeze with such an unforgiving characterisitic belongs in any vehicle, and that goes double for the leak-prone Blazer w/ Vortec engine. The web is full of horror stories from unfortunate owners who got leaks, and did not catch them in a month's time. Apparently, left unrepaired, the air will cause the Dex-cool to rust the engine, then combine with the rust and harden into an intractable mineral in the engine. It is the subject of a class-action lawsuit.

 

And the class action lawsuit will net them nothing.

Read the article posted above. The problem is not the coolant, it a lack of maintenance.

 

I agree with you, but for one issue the OEM's that use DEXCOOL then should not claim that the system not need maintanance for a period of 5years of 100Kmi which ever comes first....but as always big money company vs consumer company wins....

 

Not exactly true. The class action lawsuit will net the class-litigants cents-off coupons towards the purchase of a new GM vehicle, or if they are lucky, a $50 gift certificate. The law firm will get $12 million dollars.

Going to bat for Dex-cool is like going to bat for Thalidimide. It was a great product with just a couple of unexpected consequences. GM sold this to consumers as a 5 year maintenance-free product. As nearly as I can tell, that was true. What they failed to add was that 5 years was all you were going to get, period. Thousands of cars and trucks have been ruined by this stuff, and yes, most of those people failed to keep up with maintenance, just like they failed to keep up with maintenance using silicate-based anti-freeze. The difference was that the silicate-based antifreeze didn't harden into lava rock in your engine when you failed to check your antifreze level, or replace your radiator cap. Yes, the water pump would probably spring a leak around the seal, but that was an easy repair. I find it significant that no Japanese automaker has used Dex-cool, and GM has abandoned it in their new models. I also do not expect GM to ever admit any guilt, just like Ford never admitted their share of the guilt with the Explorer-Firestone debacle.

 

Yeah, I thought it was very informative, considering all the different things I've read in various other places.



I went ahead and topped it off with less than a pint of green, as I had no possible way to determine what is already in there, as there is red coolant that is not 'DEX-COOL', and as the report explained, it was more important to keep the level up.

I'll definitely flush the system this Summer, as it's just too dang cold to be messin' with any kind of liquid right now. What I'm going to refill it with is still up in the air.

 

Really ?

Hmmmmmmm.

 

When topping off the coolant level, do I have to mix distilled water with the dex-cool? I can't find a 50/50 premix here in Canada.

 

That's what they recommend in that report. They say you shouldn't just add DEX-COOL as you can get the mix out of whack.