Its about that time for the cooling flush and have heard about some issues with DEXCOOL. Like it doesn't mix well with tap water, air and also the havoline dex-equivalent is not recommended, etc. Have any gone back to the Prestone green anti-freeze?
Doug

 

Green stuff is fine as long as you have flushed your entire system out real well. You shouldn't use tap water, use distilled water. Tap water will cause calcium buildups in your water jacket.

 

Dex Cool is fine. The biggest concern is to get ALL of the air out of the system. The biggest contaminant of Dex Cool is air. If you get it all out and run a 50/50 or 70/30 mix you will be fine. Dex Cool is also supperior in the fact that it doesn't allow such a large buildup of silicates in the system.

 

Using distilled water will create electrolisis which will eat away your aluminum in the system. Unless you can get a zinc in there I would advise against distilled. This doesn't happen overnight but is a long term effect much like using the tap water. But at least with the tap water you can do an acid flush and get all the crap out. Your best bet would be purified or filtered water without the added minerals that some companys put in the water. The label should say what is in it. I would also suggest doing the 25/75 mix with water wetter or the purple ice. I've had good luck with this combo. But if you live where there are temps below 15* I wouldn't advise going with the 25/75 mix.

 

As far as I know "DexCool" is a trademark of GM and Texaco, jointly. Havolin (Texaco) IS DexCool, at least according to the markings on the gallon jug I have.

I ran it in my 94, with tap water for 2 years with no problems. Pulled the engine for the stroker rebuild, and the block had no deposits of any kind. Sold my radiator to a friend for his 95, and he couldn't believe how much cleaner it was than his old one.

Also been using DexCool + tap water in the stroker for 3 years, on the recommendation of the engine builder, and no problems at all, including my Griffen aluminum radiator.

I agree on the comments about the potential for increased corrosion with distilled water. When there are no impurities in the system, distilled water has a tendancy to increase the rate at which the metals it is touching go into solution. From my experience commercially designing condensate systems (= distilled water) for boilers, the condensate was considered extremely corrosive, and required significant water treatment, including oxygen scavengers, to prevent corrosion in the system. Just a thought.

 

Tap water vaires in hardness from one region to the other. Where I live it is extrmley hard water. Lots of people here get lots of deposits in the water heater, which I would think would be like water in our cooling system after a while.

I forgot about the distilled water thing. I just did heads on my car and got distilled water. I really just need purified water without the minerals in it. Glad I saw this post to remind me

Jason

 

Oops sorry dont want to stear you wrong, I thought I have seen alot of posts suggesting to use distilled water. Shows what I know

 

You can use distilled water in your battery, and that is what's recommended. It's easy to link the two, it's like hey I have the water already let's add some!

 

I personally wouldn't worry about the corrosion from distilled water - the DexCool will buffer it.

I also wouldn't worry about the hardness in tap water. The hardness only increases in concentration, and eventually precipitates out when you have a constant boiling off of the water, and replacement with more "hard" tap water. If your cooling system is operating properly, and has no leaks, you should rarely have to add water.

Flip a coin... put whatever you want in it......

 

Injuneer,
I think I got my brands mixed up. You're right havoline is the real mccoy. I was thinking of the DEXCOOL compatible prestone that wasn't recommended. Thanks.

 

Dex Cool with tap water 50/50. I flush and fill every spring and fall as part of my maintenance routine.

 

Is it true that it's not recommended to use the Prestone Dex Cool? If so, why not, and what will happen if you do use it?

 

I just picked up some Prestone Dex cool and it says on the jug "for GM cars with DEXCOOL"