Use Dex Cool in GM car or switch to universal during changeout?

I have heard all the horror stories about Dex Cool. Anyway, I have been helping a friend and neighbor with some of her vehicles. Her husband had been taking care of the maintenance but due to health problems, let many things go, thinking they had been done. This included oil and coolant changes on some of their vehicles. The coolant in one looked like rusty coffee.

One is a 2001 Cadillac Deville with the 4.6 Northstar engine. It states to use Dex Cool only on the cap. The coolant in the reservoir doesn’t look nasty but no one has any clue when it was last done so we consider it time to be done. We have a bottle of flush and some “Universal” long life coolant on hand. This coolant is the AutoZone brand and states that it can be mixed with any color of antifreeze. I have used this in vehicles using the green coolant but never Dex Cool. Can this car be flushed and changed to this coolant or should we stick with the standard Dex Cool?

I owned a 2006 Chevrolet Uplander which, on the recommendation of my independent garage, had the radiator flushed and the Dex Cool replaced with universal coolant. That was three years ago in 2010. My son now owns the Uplander and there has been no problem with the universal coolant.

When possible always get rid of the Dexcool and use one of the universal antifreezes.


The Dex Cool would be gone if the vehicle was mine. For what it’s worth, the 96 Camaro that my oldest son owns uses Dex Cool and that car went through 3 water pumps (counting the original) in about 4 or 5 years time not to mention the sludging problems.

On the last pump replacement I flushed it out, replaced with green, and never a problem since.
That’s going on 8 years now…

I would never own a vehicle with Dex-Cool flowing through it’s engine. I always flush it out and replace it with the tried and true green stuff. Never had a problem in all the years I have done it.

It doesn’t matter, but since you already have the universal, I would use it. DO NOT USE THE FLUSH chemical. Drain both the block and the radiator and then just refill with the new coolant with a mix of 2:1 antifreeze to distilled water. It will be good for another 5 years or so.

Another question… I personally own a 2000 Chevy S-10 pickup with the 4.3L. The factory fill was Dex-Cool so I always flushed and refill with it. I am still about 3 years out from my next scheduled change and that will be due to time and not mileage. Should I go ahead and change now or just not worry until the time comes and then change?

There is nothing wrong with Dexcool.

I know others diagree but I have Dex. I was concerned about it but two dealers and an independant said not to be concerned anymore. As long as it does not turn brown and there are no air leaks in the system. I have to admit I’m a little more concerned about doing work on the system myself, but so far no problems in almost four years. Use the Dex stuff though not the universal and not the flush and if its that old it needs to be changed.

So the flush is bad, even if the system hasn’t been too neglected. The Dex-Cool doesn’t look brown or broken down but we are trying to slowly do things that are overdue/neglected or the status is unknown. The timing and mileage of the last change is simply unknown in this case.

They had used some cheap crap oil and the engine stuck a ring and began guzzling oil pretty badly. I have synthetic oil in it now and seem to have gotten the ring unstuck so the oil use is only a tiny fraction of before. We plan to do spark plugs as the last change of these is unknown and the oil burning was likely not good for them.

I wouldn’t use a chemical flush but I definitely would flush it with water until it is clear. Drain then fill using distilled water and coolant.

Just curious. What ill effects have folks seen with chemical flushes?
[update: Especially if followed by a thorough water flush?]

I haven’t, but if there’s not a problem, I’d rather skip it. Used to be the only thing inside the engine was cast iron and brass, but now there are a lot of aluminum alloys and plastic that might be more affected by strong chemicals in a flush.

I would also replace the thermostat and radiator cap.
I like to remove the old thermostat and re-attach the housing, then do the water flush with the engine running and the heat on full hot to flush the heater core too.
Then put in the new thermostat and gasket.

When all is said and done…whichever you use…LABEL IT.
Especially if you change to universal, put a label with that info and change date for all to see so as not to mix it wrong at the next top off.

I agree that flushing is good without the chemicals and the universal variety of anti-freeze seems to be a quality product with no problems after many years in many vehicles.

I haven’t used a chemical flush in about 30 years now, but back when I did, I was in the Navy and had a family to support, and that meant that I could only afford used cars, and older ones at that. Every time I bought another car, I would do a major maintenance on it, oil, all fluids and a radiator flush with new coolant. After getting done, within a month or two I would start having problems with water pump leaks and hoses failing.

It took awhile to make the connection, but my mother sold me her car and I did the whole routine. Within a month I had to replace the water pump and every hose in the system. I was talking to her on the phone and mentioned it, she told me that she had just had all new hoses put on it just before she sold it to me.

I stopped using flushes after that and have had very few problems with cooling systems since then. I have used Dexcool in both GM cars and even in our Honda and my Nissan truck with no problems. Now I use the new universal longlife coolants and haven’t had a problem with them. I also no longer worry about a little old residual coolant in the system, I drain the block and the radiator, put the drain plugs back in and refill with a 2:1 ratio of antifreeze and distilled water. I use the stronger solution mainly for the additional corrosion inhibitors, I don’t really need the additional freeze protection.

BTW, I go at least 5 years between changes now, sometimes more (5 and a 1/2) and so far have not had the coolant show any signs of breakdown. Your vehicle, do what you think is right, but this has worked for me for going on 30 years now.

Double check the owner’s manual for the northstar engine. It may call for a cooling system supplement ( I think that is what it was called). It consisted of some dark brown pellets that you break up into the radiator.

@markmast Correct. On our Olds Northstar with standard antifreeze, it called for pellets to be crushed and included witht he fluid change. They were about $10 at the dealer and enough for several changes. They appeared to be more for leaks than anything else. But this is with the standard antifreeze, not Dex so have no idea if it is used with Dex or not or is compatable with Dex.

You guys are absolutely demonizing Dexcool.

We have hundreds of GM vehicles in our fleet.
They all use Dexcool
Every 5 years they get serviced, on schedule
There have been no problems attributed to the coolant

Not in our fleet, anyways

The only problem I see is if you DON’T change it on schedule.

But that is neglect, isn’t it?