When the coolant is nasty I have had good luck with the VC9 and water then drain, refill with VC9 and water, flush with the hose at the heater hose to flush heater core and hoses, and repeat untill clear. Drain all the water you can then fill with 1 gal of straight anti-freeze, then 50/50. Of course get rid of the restrictions. Also, I dont know if you guys heard about them but there are EGR cooler and Oil cooler delete kits.