'67 Dex-cool or Not

[Keating121]

Just got my first Vintage Chevy Truck!! Got it home, drove it to the coffee shop, stopped at several long lights, got there to see it boiling over, and looked orange! Made it home, figured the coolant was just nasty, added some 50/50 antifreeze and then thought, Dex-cool. I think it had Dex-cool in it, smelled like plain antifreeze?? I'm flushing the system now. It has a very new looking aluminum radiator. I'm going to go with a new 195 thermostat. Should I go with Classic Antifreeze or Dex-cool in it? Thanks!!

[67 chevelle]

flush it well
put a 180 thermostat in it
and fill with the green stuff

Thats what I would do , if its a small block , ls engine I would use dex cool

[Lee H]

Welcome to the forum. What motor do you have?
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[Keating121]

Thanks guys. Spent most of the day figuring out what engine is in it, it's a '72 or '70 350 (3970010 and front stamp has TAX suffix), has headers with duel Flowmaster exhaust and a Mallory ignition box mounted on the firewall. Don't know much else, bore, heads, cam...

[Hawghauler]

I would stay away from dex-cool. We have a fleet of GMC's and they came with dex-cool from the factory running LQ4 6.0 engines. We run power take offs with 1500RPM idles, and found our radiators clogging constantly. We switched to the green and stopped having problems. Prestone only!

Save a few bucks on antifreeze and pay lots later with rust and repairs. I've never had a problem with prestone green, but every other type I've used or had used on trucks I service, ended up with rust or clogs. I've seen f~rd 300 6's rust right through the block because he insisted on saving a few bucks on antifreeze.

Some people you can't help... spend a dollar to save a dime.

[capev86]

Dex-cool is crap....stay away from it.....it eats gaskets. Run the green stuff or the (green) stuff that is compatible with both types.

[Lee H]

Originally Posted by Keating121

Thanks guys. Spent most of the day figuring out what engine is in it, it's a '72 or '70 350.

180 degree thermostat and regular green stuff, 50/50.
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[TBONE1964]

The orange you are describing may also be sand in the casting. Some blocks did not get rinsed well from the factory and had some casting sand stuck in between the coolant jacks in the block. This was more of a common problem in the late 70's early 80's engines.

If it is casting sand, it can take forever and a Sunday to get it out. It only takes a little to turn green anti freeze orange. If the coolant test OK and you are not overheating, then I would not worry much about it.

I also agree that dex-cool is not cool

Good luck.

[randywa]

I think Dex-cool is one of the greatest products ever invented ... for making slimey mud. My wifes Grandprix came with Dex and I didn't know it needed to be changed every so often. I guess it breaks down.
Now I can't make the brown crap go away, even after flushing 6
or seven times. Just like a bad toilet.

[1project2many]

Dex-cool and many of the new "universal" antifreeze packages use organic acids as inhibitors rather than alkalines as used in traditional green antifreeze. IME these inhibitors do not like to be used in systems with different kinds of metal present. Any time an acid is present in a tank with dissimilar metals, a battery is formed and electrons start to flow from one metal to the other. And even though GM and Texaco say Dexcool is safe, I always use green antifreeze with distilled water in my own vehicles.

[68 TT]

Originally Posted by randywa

I think Dex-cool is one of the greatest products ever invented ... for making slimey mud. My wifes Grandprix came with Dex and I didn't know it needed to be changed every so often. I guess it breaks down.
Now I can't make the brown crap go away, even after flushing 6
or seven times. Just like a bad toilet.

I had a Blazer with the same problem. No matter how many times I tried to flush it out it always turned the new coolant black.

Dex-cool is nasty stuff. Stay away from it at all costs

[Keating121]

Thanks for all the input guys! I've raced motocross most of my life and have have never had any problems with Green antifreeze either, and all my race bike had aluminum radiators... I'm going with the "Old School Green!!" Love my new Chevy!! It even looks cool sitting in my driveway/garage!! Posting a pic in the pic forum, check it out!

[Keating121]

During the flush, I was running water through the engine with the garden hose with the top radiator hose off to watch for clean water and it stopped flowing after about 2 min. Not running a thermostat for the flushing... Fan was turning the whole time... Is my water pump not working all the time??? I killed the engine for a min and it was flowing again when I fired it back up. What would cause that stopping in water flow??
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[Keating121]

Moved new question to a new thread. Thanks guys!!