Changing DEX-COOL Coolant

[CEKing]

I recently purchased a ’96 Collector Edition, with just under 9400 miles. From all appearances, the vehicle has been well cared for. The only concern I have is about the DEX-COOL engine coolant. I have not yet been able to find out if the coolant has been changed since the car was manufactured. The owner’s manual says that the coolant is designed to remain in your vehicle for 5 years or 100,000 miles, whichever occurs first. The car was purchased new in September ’96; consequently, the Corvette is 7 years old. I am in the process of trying to find out if the coolant has been changed and if it has not, I am going to change it. If I do change the coolant, I will also do a coolant system flush.

I have read some horror stories on various websites about the DEX-COOL coolant. If the coolant has not been changed in 7 years, what concerns should I have and what might I want to do to possibly help avoid any problems from the coolant not having been changed.

 

[jmccloud]

Coolant

Just drain it and flush by removing the knock sensors (near the motor mounts underneath, just above the oil pan center and under two sheet metal shields).
Use water only to flush, the service manual specifically says no chemical flush. In my 95 (which uses the old green antifreeze) the manual recommends a leak stopper when doing the final fill with new antifreeze. I don't know if the DEXCOOL needs it. I got the leak stopper at the local Chev dealer (6 pellets for $8).
Use the air bleeds (maybe one, maybe two) near or on the thermostat housing when refilling and don't let the temp go over 260 F. If it gets close, turn off the engine and let it cool. Bleed more air. I had to cycle the temp 3 times 200/70F to get stable temp operation. In other words, it was 3 days before the temp quit trying to go above 230. Then it settled down and runs 195 going down the road and 215/227 when in heavy traffic.
Most of all, don't get the optispark wet. It's just under the water pump.
Good luck.

 

[Tuna]

IMO DexCool is the coolant of choice.

The horror stories you have heard are probably related to someone adding the old 'green' coolant to a DexCool system - this really messes up the system.

Since you don't know if the coolant has been changed, it's time to change it. Then you will know it is okay for 5 more years.

I'd drain and flush the system until clean water flows out then refill with the proper mixture of DexCool and water. Do not refill with the old style 'green' coolant.

 

[tlong]

Tuna,

I really looked into the whole DexCool thing. I have concluded that you can flip a coin. If you go green you can't go back to red and get the benefit of 5 years lifespan. But if you keep the red and expose it to air, possible big trouble.

The trouble came from low overflow tanks sucking air or leaky caps. That took out gaskets and made sludge.

Class action lawsuits are not a good sign either. I am a green guy now.

Tim

 

[The Car Whisperer]

Running with DexCool for 7+ years now, no problems whatsoever. Just flush with clean water until it comes out of the radiator drain and block drain plugs clean. I changed it after the first 5 years, flushed again with clean water. I also use distilled water to dilute the fresh DexCool, that way I know there is nothing inthere except pure water and antifreeze. My 86' originally came with the "Green Stuff", I havent had any problems since converting to the Dexcool.

 

[Eagle85C4]

I tried the DEXCOOL...what a mistake. I followed the correct procedure to flush and drain, replaced with the orange stuff thinking newer is better. After hitting 300°'s on the temp guage and having to replace a leaking radiator and waterpump I went back to the green stuff which works great. No more problems.
Send the DEXJUNK to the Iraqi's....that ought to be fun...

 

[The Car Whisperer]

Once again, I have not had a problem at all, been running it now for 7+ years in my 86" Vette. I have it in my 2 other vehicles also, no problems. It comes in all the newer cars now anyway. I don't see anything differant in new cars versus old cars as far as cooling system construction materials goes. Aluminum radiators are the current standard it seems and they have been used with factory fill green as well as factory fill DexCool type coolants without any problems here. I think the most important thing is to flush, flush, flush your old coolant before adding the new DexCool type coolant. I always dilute with distilled water also - that way your not adding any minerals to the coolant that may cause problems later. When ever I change the anti freeze I also add a good quality water pump lube additive to the antifreeze mixtrure. I only add it at the time I drain and flush the system. Just my experience with the stuff, I'm sure it does not work the same for everyone though.

 

[Tuna]

My 99 Buick and 03 Vette are DexCool. I converted my 92 Vette to DexCool years ago. I'm not having any problems. In fact my 92 was just rebuilt with LT4 parts and a new cam. The coolant passages in the heads and block are perfect.

If the car is a DexCool car already, keep it that way.

If you try to convert from one to the other, you better make sure you complete flush the old stuff out. The green and red/orange stuff don't mix well.

That's all from me.

 

[DAVZKAR]

Both my 91 and my 96 are now converted to green. I don't want any type of fluid in my cars that long without a change. How about brake fluid it doesn't last forever either.