Dex-cool is not my friend

[ahazuarus]

My engine cooling system has been flushed, aluminum gaskets replaced, you know, the usual overhaul when it goes bad.

This is a common problem, no news to me. But I would like some suggestions as to what coolants are less prone to cause electrochemical incompatibility and how best to convert my engine to it (if necessary).

Thanks for the help.

[geoffinbc]

Prestone all make/model best stuff I have ever used.

[ahazuarus]

Do I need to flush my system?

[geldartb]

after my intake gasket went out taking the engine with it. i can tell you that crap didnt go back in the new engine. used the normal stuff think it was peak.

[ahazuarus]

I cant say I blame you.

[geldartb]

but hey i got a brand new engine out of it. $700 for a motor with 300 miles on it.
im rebuilding the old 3400 with some nice power maker mods for my beretta.

peaks pretty good stuff. anything thats not dexcool is good for me.

[loner666]

ive heard alot of bad shit about dex-cool..heard that GM has sent emails/letters about having it drained and putting the green stuff back in..the dex-cool eats the lower intake gaskets very quickly apperently

[tractorman]

I'll agree that Dexcool is bad medicine. Just for ya'll's information, LOTS of coolant out there nowadays- including Prestone allmakes/allmodels stuff is essentially the same thing as Dexcool. They're both an OAT coolant (as in Organic Acid Technology). If you're looking at ANY antifreeze, and it says 'extended life' anywhere on the bottle... then it's a pretty safe bet that you're looking at either an OAT coolant, or a HOAT (Hybrid Organic Acid Technology) coolant. In either case- it ain't much different from Dexcool, and I won't run it in my own vehicles.

There are two basic types of 'conventional green' antifreeze. The common, run-of-the-mill green stuff that you USED to find everywhere (and is now becoming scarce) is "high silicate" antifreeze. It uses silicate as the corrosion inhibitor- and it pretty effective. But you'd better change it every couple of years or you'll experience "silicate dropout" and slime will settle to the bottom of all your cooling system components. The second type of 'conventional green' antifreeze is generally sold as "heavy duty coolant", and uses nitrite and/or molybdemate additives (often called SCA's) to prevent corrosion. It's often used in heavy duty diesel engines (trucks, tractors, and other heavy junk that I like to work on) because it's particularly good at preventing a nasty type of corrosion that certain diesel engines are prone to (liner cavitation- holes in the cylinder walls). It also works great in automotive applications, but it's a bit more expensive than the walmart stuff. I've been running it in my '94 Corsica and my '01 Lumina for years.

[ahazuarus]

I agree with the tractorman. Dex-cool is dex-cool no matter what you call it. it still polypropylene glycol. I have plenty of experience with the heavy duty stuff. I hadn't considered using it in my 3100 though.

[tractorman]

Nope... Dexcool is not propylene glycol. It's ethylene glycol just like the green stuff. In fact, despite persistant and unfounded rumors to the contrary- you can (theoretically) mix dexcool and green stuff with minimal ill-effects... but you lose the supposed "extended life" properties of the dexcool.

The difference between dexcool (and assorted other OAT coolants) and conventional green antifreeze is the corrosion inhibitor package. They're totally different.

Propylene glycol is a whole other animal- generally sold as "low toxicity" antifreeze. I've seen it sold with an OAT additive package similar to dexcool, and I've seen it sold as an SCA coolant (by Cummins). I've never seen the 'low tox' stuff cause any particular problems... but for whatever reason, some engine manufacturers insist that you'd better not use it in THEIR product. I wouldn't chance it.

[n0rt0npr0]

So what about Prestone Extended Life Antifreeze with the BLACK cap? Is there any real-world reason to think that THAT product will eat our LIM gaskets?

Or is what you're saying is just stay with the green stuff no matter what for now?

[Superdave]

I use a 90/10 mix of water and regular old green stuff.

[tractorman]

Superdave- if you're running 90% water... then you're going to have major corrosion issues.

Good Gawd... antifreeze used to be such a SIMPLE subject. That's no longer the case, and there are no longer any EASY answers.

I'm personally not convinced the Dexcool 'eats' lower intake gaskets. What I've consistently seen from Dexcool is that it turns into a nasty, sticky, and impossible to flush out brown sludge. Some folks claim that that's due to air in the cooling system, overheating, etc... and that may well be true. But the fact is that no other coolant forms this particularly nasty sludge- even under less than ideal conditions.

As for alternatives to Dexcool... substantially different (from dexcool) alternatives are becoming few and far between. Personally, I prefer green 'heavy duty' coolant with SCA additive... but you're not likely to be familiar with the stuff unless you hang around truck or heavy equipment dealerships. This type of coolant is sold, fairly commonly, as Texaco Heavy Duty coolant. I've seen it at Advance Auto parts.

As for old-style conventional green coolant... it's very hard to come by these days. Basically, if you see green antifreeze that does NOT advertize "extended life" anywhere on the bottle (nor "heavy duty"), then you're probably looking at old style conventional high-silicate antifreeze. This is, IMO, a good alternative to Dexcool... but you'd better change it every two years to avoid corrosion and/or silicate dropout.

Now, any other coolants (usually green or yellow) that are advertized as "all-makes" or "universal" are generally some alternative form of OAT (organic acid technology) coolant similar to dexcool. I've never SEEN them cause a problem... and I'd prefer them to dexcool simply because they are NOT dexcool... but I'm not sure that they're all that different.

Now, despite my abiding hatred of Dexcool... I will say this for it. I've dealt with nasty sludged Dexcool systems, and I've dealt with squeaky-clean ones. I've NEVER seen one that was in between. I suspect that if a cooling system is kept in optimum condition (no leaks, no air, no overheating, drained & filled LONG before the reccommended interval), then you'll find no better corrosion protection than Dexcool. However... if ANYTHING in the cooling system becomes less than ideal (like a leaking LIM gasket)... then that Dexcool will turn on you and bite you in the a$$... you'll be flushing out sludge.

For my purposes, I'd take my chances with almost anything EXCEPT dexcool. Some people run G-05 coolant (lots of imports use it... so does Ford) instead of dexcool with good results. I've never tried the stuff, but what I can tell you is that it uses a "HOAT" corrosion inhibitor package (hybrid organic acid technology), meaning that it's essentially a combination of dexcool-type and silicated antifreeze.

[ahazuarus]

So if I use Heavy Duty Texaco antifreeze... and flush the system every two years... I may be better off in the long run? I am looking for a good alternative that wont get me in the long run...

[tractorman]

In my opinion, Texaco Heavy Duty is a good choice. It's quite similar to the old-style silicated antifreeze, but without the danger of silicate dropout. And best of all... it ISN'T Dexcool. It isn't even similar.

Chances are that you can dump any common antifreeze into these cars without problems... as long as you change the stuff every two years. I know that the bottle will often claim 5 years/100,000 miles... but antifreeze is cheap and easy to change- unlike clogged radiators and overheated engines.