Antifreeze/Dexcool

[IRQVET]

Wow, I just had this conversation with my mechanic today. According to him, along with a mess of garage mechanics I know, all of them say to stay away from GM Dexcool.

My mechanic said he just this week had to replace the heater core on a 2004 GMC Yukon that he contributed to running Dexcool for 100K without a collant change because, from what the owner said, the dealership told him Dexcool is good for 100K miles.

Everyone told me to run green. (Prestone to be specific) and I have been running it ever since.

 

[99Yuk]

When I swapped in my new crate motor, the Mech insisted on going with green. He showed me two fully blocked water jacket holes in the rear of the old block which he said was caused by running orange. So now I'm green. I dunno, but I figured the old guy knew what he was talking about and went with it.

My old block is out in the garage, I'll take pics today and post after if anyone wants to see, but it's cold out.

 

[Billy_ocean04]

yeah i want to see how it looks

 

[Archer04]

Well I am doing the 100k service on my girl right now, wasn't done by previous owner. So far I have gotten the rear diff, oil pan gasket, and oil, power steering to include hydro boost and gear box. Still got to do the transmission, front diff, and transfer and of course the radiator. Think I will go green after a complete flush and clean, but the question I have is since it has to be flushed should I use a chemical flush with it, and let that run in the system for three days as instructions on it recommends, or just flush without a chemical flush? Any advice is greatly appreciated.

 

[TigerEyz3]

I'd do a chemical flush followed by a clean water flush to eliminate the possibility of gelling (what happens when DexCool interacts with "green" coolant), then fill with your desired coolant.

 

[Back N Black]

My co-worker and I were discussing the Dexcool crap earlier tonight. When looking at the two types of antifreeze, he poured each into cups, mixed them together (50/50 mix) and it gelled in minutes. I had that crap in the first car I ever bought new. I owned it until about 60-70k miles. This was before they apparently changed the formula though. I learned that it was supposed to be good for 100k miles. If this is true, why did it look clumpy and foamy in my car? Maybe it's better these days, but I still refuse to run it. The old green stuff has been used for about 100 years, if it's worked for so long, in so many vehicles, why switch to something that you already know is iffy?

After reading your post Archer, I really wished I had flushed my system. My lower intake manifold gaskets had fail for the third time, atleast. I found receipts showing that these gaskets have been replaced twice before. When I got my Tahoe, I knew it had issues and couldn't drive it. Luckily for me, the gaskets allowed the system to flush itself . . . right into my crankcase! No big deal, gave me the opportunity to rebuild my first engine! I should have flushed it after putting everything back together. Might have to do that soon, just in case.

As far as your question, the chemical treatment sounds like it could be kinda harsh on the motor. At the same time, I really don't think that plain water is going to flush the system. You really have no other option. Use the chemical flush, and then a plain water flush.