How bad is Dex-Cool really?

[Chris B.]

I have a 1997 Chevy truck with the Vortec 350 and it has has Dex-Cool since it was new. It was flushed and filled every 2-3 years and it has never had a problem. The original radiator was replaced because of a leak but that was 4 years ago and all is still well.
I keep seeing comments about Death-cool? Where does this come from? Should I switch over to another coolent? Thanks!

 

[defektes]

Personally i'd never use it in a motor not designed for it, like your 5.7. My LIM gaskets were eaten through, and my dads 5.7 LIM gaskets were eaten through. I'd use Zerex green in that motor, like it was intended too.

 

[justinf89]

its only bad if not properly mantained. just change it every 5 years and youll be golden. oh and dont mix it with anything else.

 

[The_Eric]

Originally Posted By: justinf89
its only bad if not properly mantained. just change it every 5 years and youll be golden. oh and dont mix it with anything else.


Agreed, plus keep it completely filled and properly sealed with a good pressure cap at all times.

 

[bullwinkle]

And keep a CLOSE EYE on the coolant level & condition-if it starts running low for no apparent reason-find & fix the problem before a CATASTROPHIC engine failure occurs due to coolant in the engine oil!

 

[cchase]

Haven't had any problems here running it for 12 years so far (knock on wood).

My understanding is that the problems usually arise with open systems and negligence more than anything else.

 

[Boss302fan]

Works great if you maintain it. Do a radiator drain and fill every other year and you will not have any problems.

 

[Bill in Utah]

In a SEALED system and changing it out every 3-4 years (or around 60k) I'd have no problems using it.

It is NOT a 100-150k mile coolant (IMO) and needs to be watched. In my 2004 GMC I went to Peak Global lifetime just because I want the same coolant in everyone of my vehicles.

My Moms 2002, my old 2000 Silverado both have had Dexcool since new with not a single issue. My 1996 Chevy 4.3l has used it and its got over 250k with no problems.

The "deathcool" is the same mindset as "Orange can of death" camp. Very little FACTUAL data to prove it.

Bill

 

[willix]

I do think the Dex cool is harder on some gaskets after a long period-say ten years or more. It will effect only certain gaskets such as the nice plastic with silicone inlayed like this-
[img:center]

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The plastic deteriorates and the silicone inlay looses its support & blows out.

[img:center]

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[440Magnum]

I just thought I'd chime in here since I've been called out as a "DexCool hater" on here before... and I don't really deny that I don't like it, either. ;-)

I think you've gotten a lot of good advice. Basically, it works just fine in sealed systems that were designed from the ground up to work with it- including gasket materials. Other chemistries are much more universal and work with pretty much any materials (PGL, G-05, just to name two).

In the case of your 1997 Vortec, there probably ARE some gasket materials in there that aren't as compatible with Dex as the gaskets going into current LSx engines. I wouldn't say they're outright incompatible, but they could be better and less sensitive to plasticization by the 2EHA in Dex. As others have said, a lot of engines of your engine's era have had lower intake gasket problems.... but not all (yours is a good counter-example).

Armed with that knowledge, I'd probably keep doing what you're doing but always keep in the back of my head that any unexplained drop in coolant level might mean a gasket problem and therefore never just keep topping off a system that's losing coolant. Maybe even do a periodic oil analysis looking specifically for coolant by-products.

For whatever its worth, I do the same sort of thing with my 2001 Cherokee- not because of the coolant it uses but because it has a cylinder head casting that has cracked in a larger percentage of engines than any of the previous or later-production 4.0 engine heads did (the "0331" head casting, which most Jeepers are aware of). Its not worth unbuttoning a perfectly running engine just as a preventative because the overwhelming majority do NOT fail, but its worth remembering that if this engine starts dropping the coolant level there is a fairly common (and potentially damaging) reason that should be checked immediately.

 

[keith]

Maybe a part of the bad rap comes from the NorthStar head gasket debacle. I flushed my DexNotCool at 50K miles and was about to flush again at 105K miles but the head gasket blew so I didn't need to

I read that about 50% of Northstars blow head gaskets by 100K miles, and mine was right on schedule. Maybe GM fixed the design by now? Mine was a year 1999 Cadillac STS.

 

[willix]

The N* pics posted are on a engine that had its first flush at the dealer at 42,000mi due to a trans cooler blowout.

I have flushed the system every 25,000mi with Prestone Dex since.

No headbolt/gasket issues. (knock on wood)

If you look close at the top picture you can see the plastic material de-laminating from the inside perimeters of those gaskets that were still intact.

When the gaskets came out they were impregnated with coolant and resembled cardboard very crumbly.

The plastic material was noticeable in the coolant as little black particulates.

This car has never overheated. 106,000mi.

 

[Chris B.]

Here is a little more back ground on my 1997 Vortec 350. It has 140,000 miles and the intake manafold gasket did leak in the oil back around the 100,000 miles mark. I caught it very early through UOA's and had it fixed right away. Is this gasket faliure because of the Dexcool? I always thought it was because it had 100,000 miles on it. How much damage will the new gasket with 40,000 miles on it have at this point? The truck has been in storage for almost 2 years and will be put back in to use soon.
If I go back to the green stuff will it be better for my seals, gaskets and engine overall? If so how do I flush it to make sure I have ALL the Dex out and only new green coolent? Can I do it with my garden hose? Many thanks!

 

[440Magnum]

Originally Posted By: Chris B.
Here is a little more back ground on my 1997 Vortec 350. It has 140,000 miles and the intake manafold gasket did leak in the oil back around the 100,000 miles mark. I caught it very early through UOA's and had it fixed right away. Is this gasket faliure because of the Dexcool? I always thought it was because it had 100,000 miles on it. How much damage will the new gasket with 40,000 miles on it have at this point? The truck has been in storage for almost 2 years and will be put back in to use soon.
If I go back to the green stuff will it be better for my seals, gaskets and engine overall? If so how do I flush it to make sure I have ALL the Dex out and only new green coolent? Can I do it with my garden hose? Many thanks!


Well, first off the original LIMs probably did fail sooner than they should have at least partly because of DexCool. 350s didn't USED to do that at only 100k miles after all.

Second- what kind of gaskets were used when they were replaced? If you can find out the brand and part number in there, someone here might be able to tell you if they are more DexCool tolerant. IF they're new and upgraded gaskets, they will probably be fine indefinitely.

If you do switch coolants, going back to conventional inorganic coolant (commonly called "green," but color means nothing) is one choice. Another would be G-05, and another would be Peak Global Lifetime. My personal pick is G-05, because Ford and Chrysler have used it with such success and I've never heard of any issues in using it in systems intended for inorganic (I've converted 2 of my vintage cars to it). I would probably use G-05 or PGL instead of conventional simply because its getting to where its harder to find a coolant that you really KNOW is an old-style inorganic additive coolant. Its still out there, and most 'store brand' coolants are still inorganic. But without reading data sheets, its a little hard to tell. On the other hand, if it says "Peak Global Lifetime" or "G-05" on the label, you know what you're getting.

Flushing- my preferred method is to open the block drain plugs on the lower/sides of a v8 block like your 350. I then flush with a "T" in a heater hose and a garden hose, and then let the block and radiator drain fully again. If the block drain plugs are impossible to get to, or you can't get them out without rounding them off, then drain as much as you can, flush with a garden hose, fill with distilled water and idle until the engine warms up fully and water circulates, drain, and refill with your new coolant. Any remaining 2EHA will be very very diluted at that point.

 

[willix]

I am not suggesting Dex-cool is a bad product. I continue to use it.

I do believe it may be harsh on some gasket materials in the long term .

GM may have dropped the ball on some of the materials used.

A 1997 Vortec is 14 yrs old now just as my Cad is & I have been chasing many nuisance problems down for the last year. It's 15 yrs old.

 

[willix]

Originally Posted By: keith
Maybe a part of the bad rap comes from the NorthStar head gasket debacle. I flushed my DexNotCool at 50K miles and was about to flush again at 105K miles but the head gasket blew so I didn't need to

I read that about 50% of Northstars blow head gaskets by 100K miles, and mine was right on schedule. Maybe GM fixed the design by now? Mine was a year 1999 Cadillac STS.

The N* headgasket failure rate is closer 0% than 1%

Headbolt failure attributing to head lift & gasket failure is around 20%. 1998 & 99 were the worst years that the block castings were flawed with headbolts failed 25% of the time.

The repair expense is catastrophic in most cases on an older car.

Cyl. blocks were unrepairable in some cases.

Gm has corrected that problem in 2002 but intern created a block cracking issue due to the deepening of the headbolt threads/longer bolts.

Dex cool has never cause a N* headgasket failure. Gm discontinued & shutdown the N* plant in Lavonia & that plant is now used for the VOLT.

 

[Boss302fan]

What year did GM upgrade the gaskets to handle Dexcool better? 03 and later?

 

[ArrestMeRedZ]

My '97 350 Vortec IMGs lasted until about 8 years and 66k miles. The truck was properly maintained by me personally. When it started leaking, I caught it pretty quickly. One of the gaskets was pretty much disolved by chemical action of the coolant.
I'm not sure of the factory replacement gaskets I purchased, but I suspect they aren't the improved ones. I installed them before I knew of the incompatibility problem. I've since switched to G-05, and have been happy with it.

 

[j_mac]

I've got a 2001 GMC full size truck with the 4.8L V8.

Am I in danger of the DexCool Death Fluid eating my gaskets, etc alive?

Should I Change the orange coolant out for a green fluid?

 

[Bill in Utah]

Originally Posted By: j_mac
I've got a 2001 GMC full size truck with the 4.8L V8.

Am I in danger of the DexCool Death Fluid eating my gaskets, etc alive?

Should I Change the orange coolant out for a green fluid?


How many 4.8l have you heard of failing or seen on the side of the road? Like I posted above I've PERSONALLY got two of them and they are fine with the Dexcool. With my 2004 I just went with something else because I wanted the same coolant for all of my vehicles.

Bill