Dex-cool and Malibus

I wanted to pass on some info about Dex-cool. Dex-cool is ethylene glycol just like the green anti-freeze is. The difference is the additive package. Dex-cool has it's pluses and minuses (I will get to the minuses), but with a few precautions you can eliminate the minuses and retain the pluses of it-better aluminum protection and overall corrosion protection, longer coolant life (maybe not as long as they say though) and longer water pump life.

Dexcool does eat the original plastic lower IMG in 95-03 60 degree v6's. But this is an issue of an incompatible and poor gasket as much as Dex-cool. A new steel gasket will solve that problem.

The second thing is Dexcool will sludge up if it is exposed to air in the cooling system. This is not really a problem on most cars because they use a closed cooling reservor with the cap on the reservor. My 97, 3100 Malibu with about 120K miles has no sludge buildup, just a leaking IMG that I'm about to replace. I can't say I'm crazy about an anti-freeze that is intolerant to air being in the system, but you have to deal with it's minuses to keep it's pluses.. If you bleed the air out of your cooling system properly and keep the Dex-cool topped up it will not sludge.

Also I believe Dex-cool can be mixed with green anti-freeze, not that I'd recommend it because it defeats the purpose of using Dex-cool. Some people said that mixing the two, would cause sludging, but I don't believe that's true.

Also, Prestone sells Extended Life anti-freeze and Dex-cool. The Dex-cool is in a silver jug. I think the Prestone Extend Life anti-freeze is for all intents and purpose the same as Dex-cool. I don't know this for a fact but I think that Prestone Extended Life and Prestone Dex-cool has the same additives. They both meet Gm's Dex-cool requirement. Prestone says Extended Life can be mixed with anything. So I think Extended Life would have the same issues Dex-cool has-eating the old desing IMG, and with air. The difference I think is the Dex-cool usually cost a few dollars more and has a different dye in it. You are probably paying for the Dex-cool trademark on the bottle, not that Dexcool has much reputation anyway lol.

I intend to stay with Dexcool and use Prestone Dexcool when I change it. I would recommend others continue using Dexcool :2cents: . Extended life might be the same thing but I want to keep the orange color. I thought I'd pass on a few tidbits that I think are from the best credible sources. Maybe I'm just trying to reassue myself in continuing to use Dex-cool :wink: .

I wanted to pass on some info about Dex-cool. Dex-cool is ethylene glycol just like the green anti-freeze is.
Hmm. Back in the mid '90s we had to take a course when Dex Cool was starting to be installed in cooling systems on a general basis and the instructor informed us that the old standby green coolant, which came out in the mid 1920's as a "permanent coolant for vehicles" is ethylene glycol , while the Dex Cool and other similar OAT and now Hybrid Oats were propylene glycol .

I can't say I'm crazy about an anti-freeze that is intolerant to air being in the system, but you have to deal with it's minuses to keep it's pluses.. If you bleed the air out of your cooling system properly and keep the Dex-cool topped up it will not sludge.
That is one of the properties of propylene glycol as it got it's start in commercial food applications and is a component of keeping water pipes in home applications from freezing. If it is exposed to air it starts to oxidize.

Also I believe Dex-cool can be mixed with green anti-freeze, not that I'd recommend it because it defeats the purpose of using Dex-cool. Some people said that mixing the two, would cause sludging, but I don't believe that's true.
It is true. I have seen it many times over the years. Most of the time it was by other mechanics who didn't know enough about the products and their differences to mix them. I'll admit even I have said it was all right to mix the 2 as close as a few years ago, but as time went on it became evident that there are issues present. The biggest issue and the main reason to not mix the 2 is that mixing causes the protection package, which is unique to the Dex cool to be rendered useless, causing your engine to not be protected, not a good thing.

Also, Prestone sells Extended Life anti-freeze and Dex-cool. The Dex-cool is in a silver jug. I think the Prestone Extend Life anti-freeze is for all intents and purpose the same as Dex-cool. I don't know this for a fact but I think that Prestone Extended Life and Prestone Dex-cool has the same additives. They both meet Gm's Dex-cool requirement. Prestone says Extended Life can be mixed with anything. So I think Extended Life would have the same issues Dex-cool has-eating the old desing IMG, and with air. The difference I think is the Dex-cool usually cost a few dollars more and has a different dye in it. You are probably paying for the Dex-cool trademark on the bottle, not that Dexcool has much reputation anyway lol.
I don't know about you but I'd be willing to pay a few extra dollars for a product that is recommended by my vehicle's manufacturer to work and protect my cooling system, after all it is my main source of transportation, and I depend on it to be there for me. I buy my Dex Cool, for $12 a gallon at my local A C Delco warehouse. I wouldn't attempt to use a "similar" product in place of teh main product, especially when the bottle says it can be mixed with other coolants. Better to be safe than sorry.

I intend to stay with Dexcool and use Prestone Dexcool when I change it. I would recommend others continue using Dexcool :2cents: . Extended life might be the same thing but I want to keep the orange color. I thought I'd pass on a few tidbits that I think are from the best credible sources. Maybe I'm just trying to reassue myself in continuing to use Dex-cool :wink: .
Good point in staying with the Dex Cool. I recommend that the Dex Cool be handled like the older coolants and changed out more frequently. I do mine anywheres from 35 to 45,000 miles or every 2 to 3 years, not the original 5 yrs/150,000 miles. Another big issue with the coolant is the original time frame set forth by GM. That lead many people to believe it was a "maintenance free" item and didn't tend to it like they should have. As a result, many issues, some described above took place leading to Dex Cool to get the bad reputation. I have had many GM vehicles over the years with Dex Cool, and have not had the issues many have reported. Part of the reason I attribute to that is proper monitoring and maintenance of the product,

Hmm. Back in the mid '90s we had to take a course when Dex Cool was starting to be installed in cooling systems on a general basis and the instructor informed us that the old standby green coolant, which came out in the mid 1920's as a "permanent coolant for vehicles" is ethylene glycol , while the Dex Cool and other similar OAT and now Hybrid Oats were propylene glycol .


That is one of the properties of propylene glycol as it got it's start in commercial food applications and is a component of keeping water pipes in home applications from freezing. If it is exposed to air it starts to oxidize.

I'm pretty sure Dex-cool and conventional green anti-freeze are both ethylene glycol. Propylene glycol is a separate class of anti-freeze and is not recommend by GM for use in place of Dex-cool. However, as far as I know even propylene glycol can be mixed with ethylene glycol which includes Dex-cool. I wouldn't mix any of the three, but I don't believe that mixing any of them cause them to sludge. What causes Dexcool to sludge in the presence of air is the additive package. With this thread, I'm trying to dispell this misinformation about Dex-cool.



It is true. I have seen it many times over the years. Most of the time it was by other mechanics who didn't know enough about the products and their differences to mix them. I'll admit even I have said it was all right to mix the 2 as close as a few years ago, but as time went on it became evident that there are issues present. The biggest issue and the main reason to not mix the 2 is that mixing causes the protection package, which is unique to the Dex cool to be rendered useless, causing your engine to not be protected, not a good thing.


There's really no good reason to mix standard green with Dexcool when there's Extended Life anti-freeze so readily available. I agree with the part you said that's bolded. However, I'd say it's the only issue and reason not to mix the two. This is one of the points I was trying to make with this thread.


I don't know about you but I'd be willing to pay a few extra dollars for a product that is recommended by my vehicle's manufacturer to work and protect my cooling system, after all it is my main source of transportation, and I depend on it to be there for me. I buy my Dex Cool, for $12 a gallon at my local A C Delco warehouse. I wouldn't attempt to use a "similar" product in place of teh main product, especially when the bottle says it can be mixed with other coolants. Better to be safe than sorry.



I agree that's it's silly to squable over a few dollars when you're talking about something as important as your engine. But again, I believe Dexcool IS compatible with the other anti-freeze. And so I think Prestone Extended Life is Dex-cool, as it meets the GM specification for Dex-cool requirement. I think the difference is the dye and you're paying for rights to label it Dex-cool. But again, I'm with you, and over a few dollars I'd rather get the right orange color and know for sure it's Dex-cool specification.



Good point in staying with the Dex Cool. I recommend that the Dex Cool be handled like the older coolants and changed out more frequently. I do mine anywheres from 35 to 45,000 miles or every 2 to 3 years, not the original 5 yrs/150,000 miles. Another big issue with the coolant is the original time frame set forth by GM. That lead many people to believe it was a "maintenance free" item and didn't tend to it like they should have. As a result, many issues, some described above took place leading to Dex Cool to get the bad reputation. I have had many GM vehicles over the years with Dex Cool, and have not had the issues many have reported. Part of the reason I attribute to that is proper monitoring and maintenance of the product,

I agree with all these points. Stil Dex-cool was incompatible with the original IMG installed on the 95-2003 60 degree V6. I would say though that Dex-cool does seem to protect longer than green anti-freeze does. The green turns acidic quite abit faster. However, I still wouldn't go over more than 4 years or say 80,000 miles before changing Dex-cool. Again Dex-cool does not tolerate air in the system so it's important to keep the cooling system filled and to fix any leaks. But that's just part of good, normal maintenance.

Bottom line, if you replace the old IMG, keep Dex-cool filled, then you will get better performance with Dex-cool than with green. There's no reason to switch from Dex-cool to green or to ever mix anything in besides Dex-cool.

Just to add my 2 cents here, my wife's 1999 Malibu 2.4 with Dexcool started to overheat at 57,000 miles. I replaced the Dexcool and the problem went away. It's probably good to replace it every 3-5 years or 50,000 miles, not the 150,000 as recommended. My wife barely puts 7k miles per year on her car so it was 8 years old at the 57,000 mark. Not surprising the Dexcool had to be replaced.