Dexcool doesnt have to have 150k to turn to mud. Just a little air sucked in to the sysetm by the ever failing lower intake manifold gasket can give you chocolate pudding. If you are lucky (I use that term with some reservation), it leaks to the outside, as mine did. If not, it leaks to the inside and mixes with your oil. Am in the middle fixing problem (1999 3.1l) at this time.