Dexcool Debate

[2kredss]

Good morni'n you all. Hope your labor day is a good one. I'm new to bobitog even though I'v been reading the forums for some time. Being a certified car nut. I have to chime in on this dexcool argument that seems to be endless. I have a 2000 Monte Carlo SS 3.8 liter that has 91000 mi. and is seven yrs. old. I bought it new.It's time to get it ready for the next 100000 mi. My wife and I love this car it's been a good one. Anyhow after draining and flushing the cooling system I was shocked at how clean the system was after all I've heard. I'm 50 yrs. old and have never seen a cleaner system. But I have all ways made sure there was no air in the system .That is where, I firmly believe all the problems with dexcool stem from. Keep the air out and I will bet you will be as impressed as I was. Awesome forum.

 

[labman]

Thank you. My Cavalier is pushing the 5 years the owners' manual recommends changing it at. It is the first car I have had Dex Cool in. From what I have read here, I think Dex Cool does very well in new, air free systems as you said. Never had the radiator cap off.

I think the only responsible choice for old, leaky systems is a PG based coolant such as Prestone Low Tox. Although it hasn't lost any coolant at all yet, likely I will put it in my Cavalier when I change. A 50/50 mixture is good down to -27, good enough for here. We haven't had anything like that here since the awful winters of 77-78. I do plan a very complete flush.

 

[Ken2]

My feeling is that the Dexcool problems were the result of GM's cheap, shoddy intake gaskets and GM's cheap, shoddy radiator caps. That's how the air got in and whatever else contributed to the problems.


Ken

 

[Shelby]

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=37;t=000690

With all do respect I thought my system which had dex ran through it was fine too. I did numerous back flushes until the water was crystal clear running through the radiator. I knew there was rust but I had no idea I had Dex Gel everywhere. How do you know your system is clean? Maybe their is dex mudd stuck to the sides of you cooling system or maybe there's not. The difference between Dex and traditional Peak type coolant IMO is that you don't have to worry about gelling with the traditional type coolants, but you have to change them more often. I think if you have a factory Dex Cool system you might want to stick with it. I would run RMI 25 in there always in case gelling starts. Maybe just adding RMI 25 will stop slime and gel buildup. If I had a car I used Dex in I would change it more than the 5 years they recommend, and really burp the system and make sure there's no air in there after a change. I'm sure there is benefits to Dex, but it doesn't mix well with other stuff and should never be used in an aging system IMO.

 

[labman]

So you support me not going back with Dex Cool when I change mine?

 

[m2200b]

I'd do that flush at 3 years or 50K for dexcool.
I'm hoping you did not wait the same 91k to do the automatic trannie but I do that at 3 years /50k on GM too.

 

[Shelby]

Labman,
Not necessarily, it isn't that simple. Dex does not mix well with other coolants, so ideally if you could find something that would flush the whole system then yes I would support or agree with that. It "might" be as simple as adding RMI25 to your Dex, I don't know for sure. I say RMI25 because it is the only product that I know of that will clean the gunk out of the radiator, but there may be other products that do the same, I just dont know of them. I think if GM had half a brain they would find research RMI25 and add it to there Coolant.

 

[labman]

If you go back to my original post, you see I said I plan a complete flush. Little encouragement here to mix anything with the Dex Cool.

 

[Shelby]

My point being that I don't think a complete flush is possible w/o a product that really works. I used the 2 Prestone flushes and "thought" my system was clean. A couple heat cycles into a RMI25 treament I found out how wrong I was, silicone mudd coming out of the woodwork. I'm not even sure that RMI25 will clean the whole system to be honest, however it does seam to break up the unseen slime in the cooling system.

 

[labman]

Where do I get the RM125? Should I run some for a while before the coolant change? Unseen slime? You can't see any of my system except the overflow tank.

 

[Shelby]

Unseen slime or Gel buildup whatever you want to call it is a possibilty. Click my link in my first post and you will see. I don't know exactly what it is but it looks like a silicone or silicate type gathering. It's brown because my system is dirty and it is sticky as ****. You don't want that slime in your system even if it's a pain to get it out. I hope your's is clean!

Lots of places sell it online, batterystuff is a popular place and sells both sizes I think. Absolutely run some before your coolant change. Put a few hundred miles and check it every couple days and see if you have any gel in your overflow. The first place I saw the gel was under the rad cap, and a couple days later the system had so much gel it was in the overflow tank.

http://www.technilube.com/products/rmi25.htm

 

[ron350]

2kredss

If you really love your Monte Carlo think about changing those plastic framed lower intake manifold gaskets.
After being exposed to Dex Cool for seven years they should be just about ready to fail.

Here is just one of many stories about 3800 II intake manifold gasket failure.
http://www.bonnevilleclub.com/forum/viewtopic.php?t=22897&highlight=A

It is funny how so many GM V-6 owners praise Dex Cool until they see there lower intake manifold gaskets.

GM’s latest L36 LIM replacement gasket is made from metal instead of black plastic.

 

[labman]

According to the link to RMI 25, it forms the gel, not the Dex Cool.

''These deposits are changed from solids to a soft floating harmless gel-like material. These dissolved solids will not recombine or form blockages in the cooling system. After a period of time the dissolved solids will purge out of the system and into the coolant recovery tank.''

 

[Shelby]

Interesting thanks for that LM. I think the Dex Gelling is well documented, that is what happens when there is air in the system or it's mixed with other coolants. I', not sure but I think the silicates in there become unstable. I've read numerous posts to this effect and RMI25 wasn't even mentioned. I wonder if RMI25 will just amplify this. I also don't think this gel is harmless, lol. It's like trying to slurp a thick milkshake instead of straight water through a straw. My engine temps shoot up when driving on the freeway, then eventually come down. I'm flushing tommorow, we will see what happens. Either way it was worth it IMO, I know my system was shot and this might save it. You could here the gargling from the water being restricted long before the RMI25, and now there isn't any gargling.

 

[Ray H]

quote:

---

Originally posted by Shelby:
I think the Dex Gelling is well documented, that is what happens when there is air in the system or it's mixed with other coolants. I', not sure but I think the silicates in there become unstable.

---

DEX-COOL® and its unlicensed clones are formulated without silicates, Shelby.

 

[Shelby]

Thanks Ray I really am uneducated when it comes to all the differences between the different coolants. All I know is there's something that causes Dex to gel or slimeup sometimes, what it is I don't know- I thought maybe it was a silicone simply because the gel in my system appears to be something like that. It is also possible that Labman is correct in saying maybe all the Gel in my system is a byproduct from the RMI25 cleaning process. I admit I am confused a little because of the many posts about Dex Cool gelling up and RMI25's cleaning process that also gels up. I am 1/2 sure Critic will come bust my chops about it, but I think there needs to be some more testing.

 

[Winston]

I switched my '95 mitsu to Dexcool after a few years of its life. It has worked flawlessly for me. I did not properly flush the original coolant either. My radiator looks clean, no slime in the overflow bottle. I do a drain and top-up every two to three years with more Dexcool. However, my vehicle has never used any coolant. I never have to top it up. Ever.

Just wanted to share my good experience with Dexcool.

 

[Shelby]

Winston, you wouldn't see anything in your overflow tank unless you used RMI25 or something similar that would take the slime and deposit it there. It's possible you have slime damage but you can't see it. This is how my system was, you couldn't see any damage but the slime build up was so bad you would hear the constrictions when the water flowed with the engine running. It's possible you system is spotless, but maybe it's not too, you can't tell by looking down the Radiator cap. My first hint besides the gargling sound was when I installed a backflow device and the inside of the hose was slimey. This slime came from somewhere, I doubt someone put lakewater in there

 

[Big Jim]

Shelby,

You're flogging a dead horse.

If Dexcool is so bad, why is everyone copying it?

Dexcool is OAT (Organic Acid Technology). virtually everything available today that is labeled as long life is OAT or HOAT (Hybrid Organic Technology, OAT with a small dose of silicate).

I'm another long time Dexcool user on cars that were not originally equipped with Dexcool.

What don't you like about Dexcool? Is it the lack of silicate gel that falls out of suspension? Is it the lack of deposits it leaves behind? Is it the way it keeps the inside of the hoses nice and fresh instead of getting them all crusted up? I don't miss the old days when it was an absolute necessity to do a chemical flush every few years. Maybe you miss them though.

It kind of remeinds me of watching a guy fix a flat tire on his 32 Cadillac Limo a couple of years ago. It had spoke wheels. It also had inner tubes in the tires. He was at the side of the road changing the inner tube. Maybe that's part of the experience of driving a vintage car. BUT I DON'T NEED THAT OLD EXPERIENCE. I like progress.

You may think you know all about the Dexcool problems but is obvious to most of us here that you don't.

So what do you want to use instead? Prestone all makes all models? It is a Dexcool clone with green dye.

 

[Ray H]

If gurgling is heard, odds are very high there's air in the system - either through leakage or improper purging. DEX-COOL (and the various dexclones) simply do not tolerate the presence of air, and this fact is both well known and frequently reported. Other than bad hoses and/or clamps, a bad water pump or radiator cap are high on the list of usual suspects. A blown head gasket is also a sure-fire way to have problems with DEX-COOL. Other coolants, notably conventional silicated and G-05 (which is also silicated but includes OAT, too)*, are much less finnicky regarding the presence of air. On the other hand, if you have compromised sealing, for whatever reason, would you really wish to be kept in the dark?

*Shelby, your assumption that DEX-COOL contains silicates in addition to OAT, in reality is a pretty accurate description of G-05...