Hey guys, I just recently acquired a 2003 TC Cartier with only 40K on it. Elderly woman has previously owned it and obviously didn’t drive it that much. I started to do a complete service (all fluids, filters etc etc) and notice when changing the thermostat and gasket that there was nasty brown sludge inside the thermostat housing. Obviously I was going to change the coolant and do a flush with prestone cleaner with the service but I’d had never seen one this dirty before. I added 5 containers of the Prestone radiator cleaner and ran the car for a week going to work but unlike my other cars when I dumped it out and added a round of clean water before adding the coolant the clean water came out just as brown as the mixture with the cleaner. So for 3 weeks now I have been adding 2 bottles of the Preston cleaner and water, running the car are for a day or two, dumping it out, putting a hose in the upper hose and spraying water through the system until the water coming out the drain plug runs clear and repeating. Unfortunately there is not really a big change. The color of the water coming out is no longer black but still a nasty watered down brown color with no change. Even if I dump the cleaner/water, add fresh and then just run the car for 5-10 minutes and dump again, the water is still nasty. Does anyone have any advice on how to really clean the crap out of this coolant system? Obviously I will continue to do what I’m doing until I get crystal clear water going in and coming out before adding fresh coolant. But I wanted to see if anyone had a better cleaning idea then what I’m doing. This worked on all my vehicles but they weren’t 1/10 as bad as this one is. Thanks for any help in advance.