Dex-cool is not my friend

[toadson]

re

What Ive found with dex cool, is that when it gets old it causes problems. My family has two fullsize 98 chevy trucks, and a fullsize van, all with Vortec 350s. All of the lower intake gaskets went bad. Most likely the reason was because the dex cool was too old, and was never changed. I think its mostly due to its age, and not the mileage. Seems like our intake gaskets went bad after the antifreeze was about 7 years old (assuming it had original in it). Of course over time you might replace a little bit of antifreeze in case of leakage, but you really need to flush out as much as you can before 5 years in my opinion. After changing the gaskets on these trucks, we havent had any problems since. I guess when they advertise 5 years, 100,000 miles, you dont really think about changing your antifreeze that much. I just thought I would share my experience with the stuff. Change it on time and I dont think it will give you any problems.

[3400-95-Modified]

I'm curious if anyone has proved that the antifreeze is what causes the gaskets to go bad, or if its the "overtorquing" of the gaskets that crack them and then the coolant pressure that causes them to break in the end.

That makes more sense to me over the gasket eating dex cool.

[IsaacHayes]

Gasket eating dexcool? Dyslexic?

But yeah I don't think the dexcool eats the gaskets, it *may* cause the plastic to become more brittle possibly. But my car has NEVER in it's life had DexCool in it, and the intake gasket failed. It was both melted/warped and cracked/brittle falling apart. Just the nature of the plastic gasket. It failed again in a few years only it was leaking on the outside this time. Same thing, warped plastic and if you tried to bend it the plastic broke apart like crispy charcoal. It wasn't cracked from over torquing just old and rotten.

[rsisbetter]

heres my question, i was told that if you flush your system out to change from say dex-cool to conventional green, or vise versa, to NOT use rural water or anything like that, because the minerals and deposits in the rural type water will cause problems with the dexcool or conventional green? since i live in the country i face this problem, so whats the deal with this?

thanks
cody

[1988GTU]

Rust will happen and deposits will form from the non distilled water. I have used filtered water and it is not that bad, but I change mine enough for it to not make a problem.

[prophiseer]

wow, where've I been? ha!

Just my two cents on Dex-Cool . . .

I have never seen Dex-Cool destroy gaskets, rust steel/iron, corrode metal, lead to electrolsis or any of that other stuff that conventional will do

But . . .

the anti-leak additive that GM adds to Dex-Cool is usually the culprit in many cooling system failures sooner or later. It's that organic stuff that has to be crushed up before being added to the system. It's meant to be able to fill in small holes or other porous areas that COULD leak, and seal those areas. But, as it ages and decays (as all organic materials do), it starts to build up along the inside of the coolant system, and can end up plugging radiator veins, heater core veins, and is usually the SINGLE MAIN CAUSE of the LIM gasket failure. This junk collects as a dark brown, almost rubbery substances that will coat everything. Once this 'mixture' comes into contact with air, it starts to harden and expand - this is where it blows the LIM, usually the two coolant chambers on the LIM near the P/S pump, where there is no flow across the manifold. The junk collects and dries up, pushing against the plastic gasket and ultimately bursting the gasket or breaking the seal. But, Dex-Cool as it ages contributes to how quickly this stuff accumulates, too (I swear it must be one of the chemicals in the antifreeze itself), and once it starts to build up, it's a nightmare to remove from the cooling system (typical flush mixtures will not remove this crap). Oh, and if you've ever seen a Dex-Cool system where someone has added conventional . . . really, really nasty.

This is all why I argue that Dex-Cool must be changed out every 6 months/30k miles just like conventional. And a CORRECT mix of Dex-Cool is with Distilled water - not tap, not spring, not purified. Distilled water contains no impurities. All the others do, and will lead to sediment deposits and other crud when mixed with Dex-Cool.

Dex-Cool, though, does provide a lower freezing point than conventional, a higher boiling point than conventional, it provides better lubrication to internal moving parts (namely the water pump - ever felt how much slimier Dex-Cool is compared to conventional), releases heat quicker than conventional, doesn't corroded metal, prevents electrolosis is dissimilar motors, etc.

But, at $10 a bottle for 100% Dex-Cool, and another $1.50 for a gallon of distilled water, it's hard to sell it to customers that don't really understand the difference; and even still . . . they don't like having to swap out their coolant twice a year either.

IMO, though - there is no such thing as an extended life antifreeze.

[tractorman]

We can definitely agree on one thing:

IMO, though - there is no such thing as an extended life antifreeze.

While I wouldn't run dexcool in my own vehicle if the stuff was free... I suspect that IF dexcool was changed out every two years/30k miles (I think 6 months is quite unneccesary), then the legendery Dexcool issues would largely disappear.

Personally, I prefer conventional green or G-05 (OAT/low silicate hybrid used by Ford, Mopar, and lots of imports- comes in every color of the rainbow).

Dex-Cool, though, does provide a lower freezing point than conventional, a higher boiling point than conventional, it provides better lubrication to internal moving parts (namely the water pump - ever felt how much slimier Dex-Cool is compared to conventional), releases heat quicker than conventional, doesn't corroded metal, prevents electrolosis is dissimilar motors, etc.

I'd be interested to see any authoritative information on ANY of these claims... I have serious doubts about all of them. The only one I can shoot down immediately, though, is the freeze/boil points. Dexcool is essentially the same ethylene glycol antifreeze that's been around since the dawn of time- only the corrosion inhibitor package differs from what your grandpa used in his '55 chevy. A quick glance at the mix chart on ANY bottle of dexcool will confirm that its freezing and boiling points are *exactly* the same as those of conventional green antifreeze.

heres my question, i was told that if you flush your system out to change from say dex-cool to conventional green, or vise versa, to NOT use rural water or anything like that, because the minerals and deposits in the rural type water will cause problems with the dexcool or conventional green? since i live in the country i face this problem, so whats the deal with this?

thanks
cody

You should always either mix your coolant with distilled water (less than $1/gal at the grocery store) or buy pre-mixed coolant... regardless of what type coolant you use. To do otherwise is just silly- and inviting problems

[prophiseer]

You should always either mix your coolant with distilled water (less than $1/gal at the grocery store) or buy pre-mixed coolant... regardless of what type coolant you use. To do otherwise is just silly- and inviting problems

that's a definite. Your best bet would be to buy 100% antifreeze and mix it yourself. IMHO, I just can't justify the extra money for pre-mixed 50/50 coolant when you're actually getting less product than a gallon of 100%.

While I wouldn't run dexcool in my own vehicle if the stuff was free... I suspect that IF dexcool was changed out every two years/30k miles (I think 6 months is quite unneccesary), then the legendery Dexcool issues would largely disappear.

I completely agree with you on that. The reason I recommended the 6months though is out of habit - but, it's because of this region where I live. Our seasonal changes are so drastic that it tends to bring all the ailing cars out of the woodwork. For example - going into our 'spring', it'll be an average of 40F one week, and then the next week be up to 70F, although nighttime temps will still drop down to low 40s with chilly wind. Then it'll be back into the 40-50s during the day, until one week when it's all of a sudden 80 outside and never cools back down. Our temps here are very much dependant on the ocean currents and temps. But these drastic changes wreak havoc on peoples cars.

30k is a defi good rule of thumb, though.

I'd be interested to see any authoritative information on ANY of these claims... I have serious doubts about all of them. The only one I can shoot down immediately, though, is the freeze/boil points. Dexcool is essentially the same ethylene glycol antifreeze that's been around since the dawn of time- only the corrosion inhibitor package differs from what your grandpa used in his '55 chevy. A quick glance at the mix chart on ANY bottle of dexcool will confirm that its freezing and boiling points are *exactly* the same as those of conventional green antifreeze.

I'm sorry, I had forgot to mention my recommendations are mostly based on my experience with the stuff, so it can be easily taken with a grain of salt. But it's been a long while since I've actually READ the back of a coolant bottle so, I'm sure there have been many changes to conventional over the last 5 years or so! Dex-Cool when it first came out was better than conventional in all those aspects. I guess I should go visit the parts store and do some reading

Oh, BTW, Dex-Cool is a non silicone based polyethylene glycol. Conventional is ethylene glycol (which, oddly enough, is a fairly common ingredient in hair shampoo, toothpaste and quite a few other things, lol!).