One of the biggest issues with Dex-cool and leaks and sludge is when people mix different types of coolant with it. That is probably a big part of the lore around it. I switched and the way I did it was do TWO flushes (once with Prestone Flush and one with just water). Then I replaced with classic "GREEN" stuff mixed 50/50 with distilled water. I can't seem to find classic green anti-freeze anywhere else but O'Reilly's now...
