customer's blazer w/ 4.3 dex-cool

[mechanicx]

I still say the point remains that OAT Dexcool requires certain precautions, namely that the system remains full and air free or sludging can ensue as seen in this vehicle.

Dexcool could easily go 8 years and not sludge. Combine iron heads, cap on the radiator, a leaky system, not keeping system topped up and you can have rust and sludge ensue within a few months and a few thousand miles. It's not just a question of changing the coolant regularly.

It's just a fact that Dexcool does not tolerate air or being low as well as various other coolants. Although if you ran green 8 years you would have corrosion problems too.

Some vehicle applications seem to have the engine coolant level higher than the raditor, with iron heads and no high mounted degas bottle/pressurized reservoir it is hard to keep air out, and rust flakes off the heads. In those situations, all the mantaining of the cap and fluid level and making sure there are no leaks while helping greatly may not even be quite enough. Besides the vehicle operate isn't going to do all that anyway.

Just because Dexcool isn't problematic in one cap-on-radiator application doesn't guarantee it isn't in another.

I still say having a high mounted degas bottle is key to making Dexcool the low-maintenance coolant it was designed to be in the first place.

 

[Stu_Rock]

+1 mechanicx and Chris142.

There is nothing wrong with Dexcool if either (1) the system is designed correctly or (2) the owner of a suboptimally designed system is hypervigilant about maintaining the cooling system.

Could a BITOG member run Dexcool in a 4.3 Blazer? Yes. Would I let the general public do it? NO.

There's absolutely no way it's defensible to say "There is nothing wrong with Dexcool. Period."

 

[Chris11]

Here's a question for you BITOG members. If air in the system can cause sludge then if I take the pressurized cap off of my reservoir then wouldn't air get into the system and ruin the DEX? If that were true how the heck can I ever check its condition. All I can see from the side is the level not the actual condition of the coolant.

 

[mechanicx]

When people say Dexcool is intolerant of air, they don't mean just exposure to air. An open jug of Dexcool, or Dexcool sitting in a reservior, or opening your coolant cap is not going to cause any issues.

For Dexcool to sludge there has to be a lot of turburlence/steam and heat as in a radiator being ran low on coolant for awhile or worse in the engine. A lot times the sludge is corrosion being washed up from metals in the cooling system that aren't protected by dexcool when the system is low and has air in it.

If you notice a lot of cap on reservior systems have an air pocket under the cap and this causes no real problems.

 

[Chris11]

I see. Thanks mechanicx for the info. I have the cap on reservoir with the air pocket underneath. I guess that's why i've never had any problems. My radiator doesn't have a cap either. Thanks again for the info.

 

[jim302]

Lots of "dexclone" coolant is sold across the country (Prestone, and a lot of store brands). A lot of this is used in vehicles that were not designed for Dex-Cool. That means there's a lot of Dex-Cool being used in cars that weren't designed for it, and there don't seem to be a lot of problems as a result of this.

There are certainly better choices than Dex-Cool for a lot of cars... especially anything Asian or European, but I don't think it is as evil as a lot of people try to say it is. GM still uses it with no problems on newer cars, and Ford is now transitioning to it.

Based on all of the information out there, it looks like there were a combination of factors that caused cooling system issues in GM products right around the time they switched to Dex-Cool. Maybe some of them were aggravated by the new coolant formulation, but that can't be the full story or they would have switched away from Dex-Cool years ago, and the "universal" aftermarket coolants would likely be based on a different formulation such as an Asian p-HOAT.

 

[SteveSRT8]

Originally Posted By: Stu_Rock
There's absolutely no way it's defensible to say "There is nothing wrong with Dexcool. Period."


Yes there is. The only thing that has ever been wrong is the conditions it was used under. NOTHING at all wrong with the coolant.

Might be a bad gasket or many other problems, but not the coolant.

You may wish to note that TWO MAJOR auto companies are now using it. Hello?

 

[Donald]

Originally Posted By: Chris11
Here's a question for you BITOG members. If air in the system can cause sludge then if I take the pressurized cap off of my reservoir then wouldn't air get into the system and ruin the DEX? If that were true how the heck can I ever check its condition. All I can see from the side is the level not the actual condition of the coolant.


If you checked it daily you just might!!

 

[Donald]

Originally Posted By: SteveSRT8
Originally Posted By: Stu_Rock
There's absolutely no way it's defensible to say "There is nothing wrong with Dexcool. Period."


Yes there is. The only thing that has ever been wrong is the conditions it was used under. NOTHING at all wrong with the coolant.

Might be a bad gasket or many other problems, but not the coolant.

You may wish to note that TWO MAJOR auto companies are now using it. Hello?


Point is other extended life coolants are more forgiving than Dexcool. And I would assume the automakers have learned some from using Dexcool and are designing the coolant systems such that they are less likely to have the problems that cause sludge with Dexcool.

And I think its unwise for someone to add Dexcool to a system that did not come from the factory with Dexcool.

 

[SteveSRT8]

Gee, I missed something then. I thought we were talking about a Chevrolet.

 

[Boss302fan]

Originally Posted By: SteveSRT8
Gee, I missed something then. I thought we were talking about a Chevrolet.


Yep a Blazer. LOL.

 

[brelandt]

well, the blazer was "fixed" by a co-worker. I ended up under the alignment rack all day. we changed the passenger window regulator with motor, stabilizer bushings both upper control arm bushings, water pump and a few other things. the next day they came back for a strong pull to the left. my co-worker apparently got "tired" and left a big neg caster. So I foxed that and then the passenger window started to only work with the switch on the driver door but not on the passenger door. This truck is just bound to be in the shop for awhile! LOL

 

[Rock_Hudstone]

Originally Posted By: Boss302fan
Here we go again... You only hear from the few people that have issues.

Few people? I've been doing some shopping for an inexpensive used car recently; 2001-05 or so GM models.

Most Dex-cool vehicles I've come across have sludged up radiators and overflow tanks at 80,000 miles or less,(sometimes much less), even when the rest of the car appears well maintained.

 

[3311]

Originally Posted By: Rock_Hudstone
Originally Posted By: Boss302fan
Here we go again... You only hear from the few people that have issues.

Few people? I've been doing some shopping for an inexpensive used car recently; 2001-05 or so GM models.

Most Dex-cool vehicles I've come across have sludged up radiators and overflow tanks at 80,000 miles or less,(sometimes much less), even when the rest of the car appears well maintained.





Your probably looking at original coolant in most cases. In service well beyond its rated 5years in those 01-05 vehicles.

 

[cchase]

Not to mention the coolant tabs they threw in these vehicles from the factory that always sludge up the reservoir caps/tanks.

 

[Boss302fan]

Originally Posted By: Rock_Hudstone
Originally Posted By: Boss302fan
Here we go again... You only hear from the few people that have issues.

Few people? I've been doing some shopping for an inexpensive used car recently; 2001-05 or so GM models.

Most Dex-cool vehicles I've come across have sludged up radiators and overflow tanks at 80,000 miles or less,(sometimes much less), even when the rest of the car appears well maintained.

I guess you should not buy those...

 

[mechanicx]

Originally Posted By: Rock_Hudstone
Originally Posted By: Boss302fan
Here we go again... You only hear from the few people that have issues.

Few people? I've been doing some shopping for an inexpensive used car recently; 2001-05 or so GM models.

Most Dex-cool vehicles I've come across have sludged up radiators and overflow tanks at 80,000 miles or less,(sometimes much less), even when the rest of the car appears well maintained.







The reason is simple. Without a high mounted pressurized reservoir/degas bottle the radiator level drops and so drops in the upper parts of the engine and corrosion ensues like OAT coolants of Dexcool and Peak Global do when they are not in constant contact with metals that they need to provide protection.

The coolant being over 5 years old and sealant tabs is not the real issue. The coolant level not remaining full at all times is the real cause. Some vehicle applications are hard to keep completely full at all times. It's just a weakness if you will of OAT coolants in systems that don't have the high mounted pressurized reservoir.

 

[Jarlaxle]

Greeen stuff worked fine for decades. Dex-cool seems to be the answer to a question nobody asked...a solution looking for a problem.

 

[Rock_Hudstone]

Originally Posted By: Jarlaxle
Greeen stuff worked fine for decades. Dex-cool seems to be the answer to a question nobody asked...a solution looking for a problem.

Right, and repairing a sludged up Dexcool system usually means replacing the radiator and multiple flushings at least, that stuff is difficut to clean out. Not to mention intake manifold gaskets.

 

[Boss302fan]

I have always kept the overflow tank filled to the hot mark, while cold... Overfilled.... Never have had a problem with Dexcool in numerous cars and I think making sure the coolant never gets low is the answer. If there is an issue, then I believe it is with the open tanks and non-maintenance. Letting the coolant get low is a no, no...

I do use green in many of my older cars but still believe you should use what the manual states to use.

I am also old school(LOL) and replace radiator caps every 3-4 years. I do this on any car, with any coolant... I believe caps are cheap insurance and if you take them off a lot, to check coolant, then they need to be replaced. Especially, with the newer caps because they are so cheaply made.