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Dex-Cool

I'm just curious about those defending dex, or more specifically those going on the offense about the green stuff. What's the problem with the green "crap"? I've heard the objections to the dex but not the green stuff. I've never had a problem with the green stuff. I heard about the problems with the dex and changed over to the green because I saw some of them. So I would like to hear the objections to the green stuff, just so I know what to look out for.
 
I talked to my brother in law, who is a tech, about this issue the other night. He made a lot of interesting points but the most important thing is if you change it out you MUST remove all the dex before putting in the green, which is almost imposible. Also make sure your dilution rates are right on. Thats all I can really remember...
 
I'm not defending DEX, it's just that my truck came with it and I'll change it out every 2 or 3 years and call it good. The green stuff is ok, and I used it in everything until I bought cars with DEX.

I have been told that mxing green & Dex will cause the Dex to gel. So getting ALL of the Dex out before going green is a must, and may be a PIA.

I say, it's your truck, do whatever blows your hair back...:biggrin5:
JP
 
I don't really know what the deal is with Dex. Every GM I have owned I have had water pump issues with them. I did switch my coolant out and installed our coolant filter kit and Have not had issues since. Both problems were on my LS based gassers.

I run ford gold in our superduty and F-150. Both also have coolant filters
 
I change mie in the winters normally or whenever it is cool I pull the rad hose and put the garden hose onthe intake side let the motor idle for about 15-30 min and the pump can do it's thing and flush it out, then I just flush the radiator and the dex is gone. I disagree with the statement earlier abou the late model motors I gasket erroision in the head gasket at 80,000 miles the stuff is deadly.
 
I know this is an old thread, but after doing a search I found it and thought I would just continue on this discussion.
I never really realized there were some head gasket issues with the Dex Cool until just the other day a guy at the dealership mentioned it. I am going to flush out my cooling system soon, before winter. Some people recommend getting out the Dex Cool, some say leave it alone.

You guys had any problems that you could contribute to Dex Cool? If you drained it out and went back with another type, what did you use? Just looking for some guidance from you guys.
 
At the shop we have seen ALOT of corrosion issues with dexcool. 99.9% of the time due to lack of maintenance, or the adding of water that wasn't distilled.
dexcool, and similar coolants, have better/faster heat transfer capability than "green stuff".

I personally use CAT coolant. Never an issue. DO NOT use fluids that "meet CAT specs". Saw too many failures with that stuff.
 
The majority of dex-cool problems was early on before people understood how it needed to be maintained, or what kind of cooling system they work best in. if you notice since dex-cool came out GM has gone to pretty much all degas bottle systems where they have a air pocket in the top of them. The big problem with dex-cool early on was it would corrode and react with minerals in the water. Use distilled water and a quality dex-cool anti-freeze and stay with it. DO NOT, I repoeat DO NOT mix any other anti-freeze with dex-cool. And switching from dex-cool back to green will in many cases take out your water pump seal and heater hoses. I believe in using what a vehicle came with from the factory, do not mix different kinds of anti-freeze, and whatever you do don't use the universal crap.
 
If I was going to replace Dexcool, the last thing that would go back would be green anti freeze! I have a 55 gallon drum of Chevron Extended life antifreeze in the shop that was oem fill in many CAT applications, it is red in color and is pre-mixed, there are also other good extended life anti freezes, but I would never go back to green. Green causes lots of problems. For what it is worth, both of my duramaxes are still running dex cool, I have replaced water pumps in both of them and the aluminum was spotless, clean, and no corosion at all. I have also converted other diesels to dex cool and never had a problem. This included a 24v cummins conversion in a 85 suburban.
 
The “Green” coolant historically contained microcrystalline silica as an anti-scaling agent. This agent scrubs off mineral deposits from the internal surfaces on the cooling system. It worked rather well at that, but the down-side was the slightly abrasive qualities would eat up the water-pump seals. Decades ago it was normal to swap W/P’s ever 60-80K miles due to coolant flowing out the weep hole(s).

Dexcool (Organic Acid Coolant), the bane of 90’s era GM!:9898:
Some people love this stuff, then there are the 10’s of thousands that hate it.
Any gasket that operate with exposure to it, needs to be specifically engineered to not disintegrate in its presence! For over a decade GM refused to publicly acknowledge that little bit of data, because they themselves didn’t fully understand the extent of the issue. Head, Intake, Coolant crossovers, Thermostat, etc Gaskets were failing at an unprecedented level.

Then came the revelation that the stuff is extremely intolerant to oxygen exposure when at operating temps. IE, if the coolant system had an ambient pressure overflow can, with vacuum based coolant recovery system your Dexcool was destined to become the dreaded DexSludge.
Hence why all MFG’s that utilize Dexcool variants now have closed-loop, pressurized overflow/degas tanks!

Dexcool works well in a properly engineered system, with specific gasket material, and a fully sealed cooling system. But if you develop a pressure leak, god help you! DexSludge is a fricken nightmare to deal with, and I’ve seen it many times in person! I myself got rid of Dexcool in all of my vehicle as soon as I could!

A good substitute coolant that I use and really like is Zerex G-05, its made by Ashland Oil (Valvoline).
Its going into my Otimizer 6500, once it's back together!
You can check out the specs here: http://www.valvoline.com/pdf/zerex_g05.pdf
 
I personally don't like the G-05. It is a very oily coolant compared to regular green or even dex-cool, and it runs hotter. I had it in the VETTE I'm working on now, and it would hit 210-220 pretty quick with it. Switched back to ZEREX green and it would only get up to 195-200 by doing nothing but changing coolant. And the current DEX-COOL is not the same as the early stuff, and isn't that bad. I still get a kick out of guys draining out dex-cool because they call it dexsludge or think it eats gaskets, and put in CAT ELF saying it's so much better when it is the same basic anti-freeze with just a slightly different dye in it.
 
The biggest thing is that Dex when mixed with standard green coolant turns into the dreaded sludge, which can be nearly impossible to get out.
 
There's been talk here about Zerex being the "real" DexCool but the other one I found was Chevron-Havoline that appears to be the OEM equivalent (if not the actual OEM fill). This appears to be another choice and I've also used it with OEM filled systems to top off with no adverse effects.
 
btfarm said:
There's been talk here about Zerex being the "real" DexCool but the other one I found was Chevron-Havoline that appears to be the OEM equivalent (if not the actual OEM fill). This appears to be another choice and I've also used it with OEM filled systems to top off with no adverse effects.
Click to expand...

I like ZEREX as I haven't had any of the mud problems with it, and it has a good lubricant package in it that seems to work good at keeping the seals good. Knock on wood I have yet to have a water pump leak when using it. I know that ZEREX used to be made by VALAVOLINE, not sure if it still is or not. GM at one time was using PRESTONE for there dex-cool supplier, not sure if they still are or not as I know PRESTONE was the ones that made the early formula with all of the problems. You can always tell PRESTONE from the others as it just has it's own color hue and smell to it that the others don't have.
 
So, when I was doing testing on THOUSANDS, literally, of gas and diesel engines (yes 6.5s and the then new duramax and Cummins 235 hp) while working for an oil company (cant say who or why) testing different oils and fuels these problems arose. Due to the complexity of the problems the engineers (cant say what manufacturer they worked for) we were working with had us flush the system with an acidic cleaner, then tap water. We then refilled with cheap-o-green 50/50 using tap water, and it is HARD water here (minerals in water help contrary to old wives tales, we tested that too). Most of the actually driven cars and trucks were getting 150,000 + miles yearly. Yes some at 10,000 miles per year (can you say co. car w/ free fuel- woohoo).
The shelf mounted ones were abused harder and ran the equivalent of about 300,000 per year. WAREHOUSES full of engines and test equipment. Did I say thousands?

All automotive manufactures were required to make certain government induced improvements. gm bit the bullet on coolant and it failed. google lawsuits. not just the state based but corporate ones. If that doesn't enlighten you I say good luck. Alot of people say "just change it out every couple years..." It was supposed to be 100,000 mile coolant. It passes that test provided it is done in a 21 month period, did not get overheated, and did not have an air breach. Give me a barrel of it and I will use it to wash the mud off my truck before I put it in my radiator (my 2cents).

I spend $ on test kits and make sure all metallic parts have a good ground. Electrolysis erodes parts. Thermostat housing #1 victim, radiator #2.

As for the big truck engines and industrial engines they are wet sleeve and require much higher levels of nitrates. That is all the "coolant filters" are is a can with a tablet inside for slow release instead of monitoring close with test kits. Too much gums the works like brand (de)X. Add a nitrade filter to that and watch the fun.

3rd & 4th cents- I also will NEVER use peanut oil diesel fuel regardless of additives I will and do dump my used delo 400 through a tshirt into my tank (for off roading purpuses only, as I would never dodge a street use fuel tax). Lil hint there- can't say any more from nondisclosure agreement. other bios ok. Use good additives the research is worth it.

Wish I could talk about current job, interesting stuff. *Hopefully in a year or so...until then, keep recycling it helps the planet.

6.5ers- warehoused 6.5s all pmd were PMD. not 1 failed - heat was there varied vibrations and engine speed changes. IDK why.
 
This discussion is all well and good Will, and I appreciate it alot, but I need to change my factory fill before I take a 1000 mile run to Colorado in a month and since I'm embarrassed :o to say (sort of) I have 220k+ trouble free miles on the OEM, shouldn't I be reasonably confident that today's Dex is a whole different deal than the early lawsuit days?
 
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