coolant system flush is easy. just carefully drain the old coolant out, and properly dispose of it. take out the thermostat, and put the thermostat housing back on the LIM. fill the whole system with H2O, and run for a couple of minutes WITH THE HEATER OFF. drain. Repeat as necessary. Install the new thermostat (~$5.00, i think), and refill with 50/50 coolant/H2O. done. and not very expensive at all.