Dexcool mixed with Antifreeze (green stuff)
 

I am hoping someone can offer me some advice. Apparently one of the moronic previous owners of my car added green antifreeze without fully flushing the dexcool out of the system. I found this when changing the power steering pump and flushing the coolant... there is a nasty brown sludge. I ran distilled water through several times until the water that came out of the radiator was clear, but I can still see sludge in the radiator. I flushed as well as i could and put dex back in. Is there something more I can do to fully clean this system out and make sure there is no residual slush - particularly in the engine block?

If it matters, the car is a 2002 WS6 Trans Am with 52,000 miles on it.

Thanks in advance!

rust and scale are inevitable in your coolant system, sounds like you did an alright job at flushing it out you could take it to have it flushed but personally i think you will be alright, i did the same thingk back before i knew you werent supposed to mix the two and i flushed it with clean water just like you did and haven had a problem with it since

its not rust or scale you should be worried about. nearly everything on the motor is aluminum anyway. dexcool is a plastisizer, which means when exposed to air, dexcool will eat away and melt plastic. there is no benefit to running dex over green other then the fact it may last longer. it doesnt cool any better or more efficiently. many people drain out the dex and use regular green, which is what you should do.

if you keep the dex absolutely full, without any room for air bubbles, it will be alright. but since it was probably already low, and the other owner had to add some, the damage is done. the brown sludge is melted plastic, not rust or scale.

I'm not too big on chemical additives, but your case calls for it.

I would add some type of "rad flush" and follow the instructions on the bottle. And do the whole procedure twice. Then refill with 50/50 Dexcool & water.

Thanks for the responses! I am planning to pick up a new reservoir since that seems to be where the worst damage is... the inside of the radiator has some, but not a lot of floating gunk. My concern is less about the radiator, hoses, etc (these are easy/inexpensive enough to replace)... I am more concerned about the engine block. EchoMirage, you seem to know a bit about what happens when they are mixed... do you think there could be damage to the block itself?

What choice do you have now?

Old coolant can eat aluminum by electrolysis (sp.?), but I wouldn't worry about it. Your block is probably o.k. Don't borrow trouble that you don't have.

Flush it out as best you can and keep on truckin'.

Good advice, and if you are a person that worries, take $99 out of your checking account and get your car to a professional who will have your system hooked up to a machine that will totally flush your coolant system and replace it with the proper Dexcool mix. I have used Dexcool for 14 years now in 3 different GM products and never an issue if you change it every 30k miles or 5 years, whichever comes first. You have a nice decent mile car and this very minor cost is well worth it.

Thanks for the advice everyone... I feel better based on what I am hearing. I was under the impression that this was a far more severe issue. I think that when I have a little more time I will replace the thermostat, check the water pump and flush the engine block directly while the thermostat is off. Then I will flush with a radiator flush a couple of times and put in some fresh dex (again). I appreciate all of the support here!