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Flushing dexcool sludge

I need to flush out the cooling system on my wifes 2003 olds Silhouette. It looks like I am facing both issues of old dexcool sludge/mud, and the effects of green antifreeze being added at some point. We bought it used so I have no idea of the history.

Anyway, I’ve tried the off the shelf flush from the parts store and it didn’t cut it. has anyone found a product to cut that sludge??


You need to flush the system entirely then use something like peak global as a replacement. Sludge with dexcool is many times associated with air being introduced into the system, so you should check pressure and any coolant loss sources also.

Thanks, I did flush the coolant, but the system is coated with the brown gunk.

GM itself has a flush procedure for dexcool sludge, do a general Service Bulletin check for the product GM recommends.Dont expect the overflow bottle to come clean and the heater core may not come around, what area is giving trouble?