Can I mix the new prestone universal coolant safely with Dexcool?

[wymi]

I want to get rid of the Dexcool in my 01 Malibu. My idea is to drain out all the dexcool from the radiator drain and the overflow tank and then add the Prestone unversal and run it until the thermostat opens. Then let it cool enough to do the whole process over and over again until I have nothing but the prestone in the system. Will the Prestone be ok in with the Dexcool until I get all Dexcool out and have nothing but the Prestone in the cooling sytem? I don't want to pay someone to flush the system, as I prefer to do my own maintenance. I figure the cost of a few gallons of coolant and distilled water are still less expensive then the cost and time of taking my car to a shop.

 

[7TFord]

After draining your rad and the overflow tank rather than adding the Prestone I'd just add water and repeat the process until you have only clear water left in the system. Then you'll just need to add enough Prestone coolant to arrive at your desired mix. You can do this procedure with the rad cap off which means you won't have to wait for cool down each time to drain the rad.

P.S. What's wrong with the Dexcool?

 

[wymi]

I get the brown sludge on the radiator cap and some in the tank, I am hoping the Prestone does not have this sludge build up. Are you saying leave the cap off the tank and run the motor until the thermostat opens up?

 

[7TFord]

....Leave the rad cap off and the coolant will still circulate but won't pressurize the system, allowing you to drain the coolant right away after it circulates a few times through the block. I've heard that the Dexcool will react with Redline Water Wetter creating sludge but not on its own. How old is your existing Dexcool mix?

 

[ChrisW]

The new "prestone mix-all universal" is the same formulation as Prestones' orange dexcool, minus the dye color(s).

 

[wymi]

I did a drain and refill of the radiator and overflow tank about one year ago, so it has about 15k miles on the drain and refill. I am getting a small amount of the brown sludge build up again on the bottom of the cap. I have read that Dexcool gets this brown sludge when it has contact with air, it seems impossible for it to not have contact with air in the overflow tank, that would explain why it gets the brown sludge in the tank. I just want to get the dexcool out and put in some coolant that will not have any of this sludge build up. Is GM still using Dexcool in the 05's?

 

[7TFord]

Don't know if GM still using Dexcool but will have to assume so. Maybe small amount of sludge after 15K is normal. Not sure if the coolant change over will fix your slight sludging. Make sure you do a good system flush with water before adding coolant to get rid of any particles, and if you didn't do it before remove the overflow tank and wash it out thoroughly as it usually has sediment in the bottom. What shape is your rad in and how many miles are on your vehicle?

 

[wymi]

Can't see in the radiator, the pressure cap is on the overflow tank. When I drained the radiator last year it all came out clean. I have 42k on the car, and it uses no coolant at all.I did take out the overflow tank and rinsed it real good to get all the sludge out. So what da ya think about my slow drain and refill process, is the mixing of the Prestone and Dexcool gonna be a problem. I just prefer to do it this way if it will mix ok with no side effects.

 

[REDDOG]

My parents just bought an '05 GMC Sierra and it has Dex-cool in it.

 

[srivett]

You do not need to mix in any coolant at first. Dump the old coolant, fill it with water, crank the heat on in the car, and run it with your foot on the pedal until the rad fan comes on. Then shut the car down and let it cool a bit before dumping the water. Do this until you are happy with the look of the water. With the system drained you now put in the coolant (you put in half of the factory listed capacity). Then top it off with water without measuring. You do it this way as you'll never be able to get the system empty enough to pour in 50/50 premix. You'll end up with diluted coolant doing it that way.

Steve

 

[srivett]

I would leave it off, there will be less chance of burning yourself.

Do get the rad cap tested or simply replace it. I get my dealers parts guy to test the rad cap for me, if it looks to be a problem I have him test a new one. If the new one fails (holds too much pressure) I just keep the old cap. I figure it's just a problem with the tester at that point.

If you check your manual you'll probably see that you need all new hoses too. If you can afford it replace them and keep the old ones in the trunk as spares.

Steve

 

[wymi]

quote:

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Originally posted by srivett:
You do not need to mix in any coolant at first. Dump the old coolant, fill it with water, crank the heat on in the car, and run it with your foot on the pedal until the rad fan comes on. Then shut the car down and let it cool a bit before dumping the water. Do this until you are happy with the look of the water. With the system drained you now put in the coolant (you put in half of the factory listed capacity). Then top it off with water without measuring. You do it this way as you'll never be able to get the system empty enough to pour in 50/50 premix. You'll end up with diluted coolant doing it that way.

Steve

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Should I leave the radiator cap on or off the overflow tank when flushing this way?