sludge in aintifreeze

[rifsm1]

I've got a 2000 Firebird and checked the antifreeze and there was sludge on the dipstick. Anyone know what would cause that?

[FTA1995]

You need to determine if it's just some high viscosity stuff that built up in your cooling system, or if the sludge is actually from oil coming through the block somewhere. If you have dexcool, it could be that. Some guys swear by it, I'm not one of them.

[Trash man]

my guess is the dex-cool since 95% of the time that is the problems, you need to flush the system really well and refill it with the proper ratio(i do a 50/50 mix) its up to you if u want to go to green or dex cool

[Injuneer]

When was the last time the system was flushed, and the coolant replaced? This is a required maintenance item.

Is it possible someone has added conventional (green) ethylene glycol coolant to the Dex-Cool (orange) extended life ethylene glycol that your car left the factory with?

Is it possible the system is not being kept full, and there is air in the system?

[Al 96 Ram Air T/A]

If it looks like brownish-black "snot", then it's most likely the leak-stop pills added to the Dexcool. While it does look nasty, it won't harm anything.

I believe the preferred "pills" were made by Bar's Leaks as seen below:

http://www.barsproducts.com/PLT11.htm


I've used Dexcool in all of my cars since 95. Yes, you'll find reports of people who hate the stuff. Personally, I've never had any issues. After my latest rebuild, I did quite a bit of custom hose routing. I had a very tiny trickle of coolant coming from somewhere on the front of the engine. After weeks of trying to find it (it would never be visible on the ground, but I could smell it every so often) I threw in a bottle of the GM recommended pills, and it stopped the issue completely. However, I know I'll probably see the black goop on my dipstick in the future, as it gels when exposed to air.

I do my own powerflush every 4-5 years, and never have any cooling issues due to the leak stop.

Feel the "sludge". If it's almost rubbery, then it's the pills. However, it should not be tar-like or oily. If it is, it's oil getting into the coolant. The same thing with foam, or as we call it in the petroleum industry, mousse. When oil absorbs water, it looks very much like chocolate mousse. If it's this stuff, you have an oil leak somewhere.