Dex-Cool Is A Good Coolant

[Mr. Boston]

How many years have radiator caps been leaking...100+ perhaps? Wouldn't you think just ONE engineer would test this before Dex-Mud was unleashed on their paying customers!?

Perhaps they did and considered it just one more profit generator...

 

[Al]

quote:

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Originally posted by JHZR2:
no, what is called dex-clog...

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I'm a believer, it clogged my heater core in my 01 Sentra. As you said it could have been because there was some residual green left in there or p0ossibly because my Nissan Sentra has aa non pressurized overflow tank. If you have either of these conditions, get rid of Dex-cool yesterday.

 

[JHZR2]

quote:

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Originally posted by Mr. Boston:
How many years have radiator caps been leaking...100+ perhaps? Wouldn't you think just ONE engineer would test this before Dex-Mud was unleashed on their paying customers!?

Perhaps they did and considered it just one more profit generator...

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Most radiators that Ive seen dont have their neck comung up at an angle. This makes the radiator cap sit at an angle, and from what Ive read, is part of the issue.

Ive not had any issues with that, and about 50% of my time using an OE cap, 50% using a stant cap...

 

[Ray H]

quote:

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Originally posted by Al:
I'm a believer, it clogged my heater core in my 01 Sentra. As you said it could have been because there was some residual green left in there or p0ossibly because my Nissan Sentra has aa non pressurized overflow tank. If you have either of these conditions, get rid of Dex-cool yesterday.

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I used Texaco DEX-COOL(tm) in a '96 Accord and am using SuperTech "All Makes" (a "dexclone" extended life antifreeze supplied by Prestone) in an '03 Sonata. The Accord ran three years on the stuff. The Sonata just turned twenty months. Neither car had/has any cooling system issues and both had/have a non-pressurized overflow tank. I suspect you had some air entry or were unable to fully "burp" all remaining air out of the system after installing the DEX-COOL(tm). Prior coolant contamination of DEX-COOL(tm) isn't considered problematic unless its overall concentration is in excess of 10% of the cooling system capacity. There's also the possibility that there were pending problems that just hadn't surfaced yet prior to the coolant changeover. I don't believe even the staunchest DEX-COOL(tm) supporters (I freely admit I am one...) will dispute the overwhelming evidence that DEX-COOL(tm) will NOT mask underlying problems. But, in a well designed and maintained system, the technology works. Not meant as a general indictment of all owners, but owners who are less than vigilent* about their cooling system are very much at risk of disaster with DEX-COOL(tm). (You can generally tell who they are when hot weather arrives. They're the ones pulled over to the side of the highway, hoods up, scratching their heads with one hand and holding their cell phone with the other.)

*As far as I'm concerned that means checking the coolant level at the radiator or pressurized overflow tank at least weekly before the engine is started initially. If the coolant level isn't right up to the radiator fill opening's sealing ring or the pressurized overflow tank shows no coolant when cold, there's a problem that needs to be dealt with ASAP.

 

[Al]

quote:

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Originally posted by Ray H:
I suspect you had some air entry or were unable to fully "burp" all remaining air out of the system after installing the DEX-COOL(tm). Prior coolant contamination of DEX-COOL(tm) isn't considered problematic unless its overall concentration is in excess of 10% of the cooling system capacity.

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I am fanatical with cleanliness. I changed out the origional coolant at 20K miles and replaced with Dex. A week or so later I did another changout with Dex. I use only RO water. I replaced radiator caps and I periodically check the system to insure that it is up to the top ofg the radiator neck ( no air)

20K miles later, I had DexBrick. The service manager at York Nissan is pretty sharp. He said he has seen this before with Dex..he didn't know why but he sees it.

Like I said, I'm a fanatic when it comes to changing fluids/cleanliness. That's why I was so upset. I just don't expect this crap. BTW, the reason that I found it is bc it had eaten a hole ion the heater core.

 

[Ray H]

quote:

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Originally posted by Al:
That's why I was so upset.

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Yeah, I kinda got that part...

 

[Buford T. Justice]

Al. I am not doubting your experience whatsoever. I am confused how coolant could have done that. How could it physically transform from a liquid to a solid? There would have to be a chemical change for that to occur. What could have contacted the coolant?

Let's examine...

1) AIR. I can't see how air could do it. Many of those GM coolant overflow tanks are exposed to air either through the overflow tank's overflow line which leads to the bottom of the vehicle or the overflow tank's cap which can have openings in it in case the overflow tank overflows. Would not the coolant in the overflow tank turn to mud if air was the culprit?

2) HEAT. Possibly, but the coolant is designed generally to withstand a boil over to 250 F on average depending how much water is mixed with the coolant. It would make sense if the coolant level was low in the radiator how corrosion would form and then get mixed into the coolant as operating temperature is reached. Would this corrosion collect somewhere like the heater core and clog it? I guess that could happen, but would it look like mud?

3) Green coolant. I have heard numerous mechanics say to never mix green and red coolants or not they will sludge. I am not sure there is any truth to that. Perhaps there is a chemical reaction between the organic chemicals in red with the inorganic chemicals and compounds in green (silicates, phosphates, etc.)

4) GM coolant tablets. I honestly think these are the likely culprit if a leak does not exist. I have no proof of this, but it would make sense how the material these tablets are made out of could collect in the coolant passages of the engine and the heater core. I think GM goes overboard with these.

 

[Winston]

I converted my '95 Mitsu Montero V6 over to Dexcool back in '98. I did not know any better, but it has worked great. Radiator (brass/copper) still looks nice and clean. I have 163,000 miles on her. I do a drain and top-up every 2-3 years.

 

[BlazerLT]

quote:

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Originally posted by Buford T. Justice:


4) GM coolant tablets. I honestly think these are the likely culprit if a leak does not exist. I have no proof of this, but it would make sense how the material these tablets are made out of could collect in the coolant passages of the engine and the heater core. I think GM goes overboard with these.

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They are ginger root and won't clog the passages at all. They only expand when they get exposed to air which shouldn't be happening in a properly purged cooling system.

 

[lght1]

Hi

I dont think that air in the system causes dex to turn to mud..but rather the material described as mud is likely sealer and rust.

remember, that oat technology needs to eb in costant contact with surfaces to provide protection. so, if air is present, in a ver short period of time...corrosion. silicates are indeed missed.

 

[unDummy]

The only problems with dexcool are the owners that think it will last forever.

I have converted several cars to it with no issues.

 

[johnd]

I've had really good luck with Dexcool but I wouldn't have the nerve to leave it in a full 5 years. I change out half every two years which seems to work really well and is easy because when you pull the plug on the radiator, that is how much actually comes out.

 

[TitaniumGT]

i dont understand why you woudl swich any car TO dex-cool.. just use whatever came in it oem.

if it had dex, and its working good, then use it.. if it had green, then use it and change it every 2 years like youre 'sposed to.

i have the original dexcool in an 01 tahoe with 70k and its still perfect orange and clean.. i also had it in an 05 impala and it was labeled by my dealership as the cause of 2 blown head gaskets and ruined intake gaskets.

 

[Ray H]

Your dealership's blowing smoke. Earlier GM gaskets on plastic intake manifold "V" engines "blew" regardless of antifreeze chemistry. Hopefully their current gasket for plastic intake manifold engines is the answer. Too many owners of other makes - some never recommended to use DEX-COOL(tm) - did just dandy on the stuff over extended drain and flush intervals for the "deathcool" myth to be given further credibility.

 

[BlazerLT]

quote:

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Originally posted by Ray H:
Your dealership's blowing smoke. Earlier GM gaskets on plastic intake manifold "V" engines "blew" regardless of antifreeze chemistry. Hopefully their current gasket for plastic intake manifold engines is the answer. Too many owners of other makes - some never recommended to use DEX-COOL(tm) - did just dandy on the stuff over extended drain and flush intervals for the "deathcool" myth to be given further credibility.

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Quoted for truth.

 

[JetSnake]

What ever the cause was, I know Dex-not-so-cool failed me by turning to mud. I've owned my 99 S-10 since new and performed all maintenance myself. No green was mixed with the Dex. My problem was so bad that I was having drivability issues. The cooling system was so clogged up that the transmission cooler inside the radiator could not do it's job, causing the transmission to over heat which caused the transmission to shift so hard that it would chirp the tires when it shifted from 1st to 2nd. The first time it happened I thought I got rear ended, it was so violent.

I could not get it clean enough after a few flushes. I covered up the problem by adding an external transmission cooler. I didn't want to do that, but figured every vehicle could benefit from one.

I'm flushing the system again and switching over to the green, as I did with my wife's 98 Lumina.

This is my first post. There is a lot of good info on this forum.

 

[BlazerLT]

The problem is NOT the coolant, it is the faulty AC Delco cap on there causing air to enter the system and make it turn to mud.

Replace it with a stant and you will no longer have any problems.

 

[Al]

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Originally posted by BlazerLT:
The problem is NOT the coolant, it is the faulty AC Delco cap on there causing air to enter the system and make it turn to mud.

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Thats probably true and therin lies the problem with using DexCool in an open system where dissolved air is constantly sucked in via the unpressurized overflow tank.

 

[George7941]

My interpretation of Al's use of OPEN and CLOSED is --- OPEN = non-pressurized overflow tank, what cars have. CLOSED = pressurized tank aka surge tank, what diesel-engined vehicles have. With the overflow tank the volume of air expelled on heating and drawn back in on cooling is exactly equal to the volume expansion of the coolant. With a surge tank with the proper level of coolant very little air is expelled because the air inside the surge tank will compress to accomodate the expansion of the coolant. In fact with the right level of coolant the system becomes truly closed because no air will need to be expelled and no fresh air is ever in contact with the coolant. However I think the problem is not the coolant being exposed to air but the metal surfaces inside the cooling system being exposed to air that causes formation of sludge. So I don't think overflow tanks cause problems with OAT coolants.

 

[BlazerLT]

quote:

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Originally posted by Al:

quote:

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Originally posted by BlazerLT:
The problem is NOT the coolant, it is the faulty AC Delco cap on there causing air to enter the system and make it turn to mud.

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Thats probably true and therin lies the problem with using DexCool in an open system where dissolved air is constantly sucked in via the unpressurized overflow tank.

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Actually no air is brought into the system if the overflow tank is kept up to a proper level.