I know that there is another recent thread that has at least a similar issue but my concern is much narrower in scope than everything described in that thread so I created a new one rather than piggyback on his. I'm having an issue with low coolant temp and sticking thermostats after track days. My car currently has 3300 miles on it and I'm going to be replacing the thermostat for the second time in 500 miles- each time after a couple of track days. The first time I replaced it with a Motorcraft thermostat and refilled the cooling system with coolant meeting Fords specification. Now that I've had a couple more track days I'm going to have to replace the thermostat again. I normally complete minor repairs on my own since it's a hassle to take time off work and take the car to a dealer for a repair in which they may or may not actually resolve the issue. I know that there is some concern about residual sand and casting materials being left in the block. Is there a way to drain and flush the block without taking it in to the service department? Will flushing the block actually resolve the issue? Are there any other thoughts or suggestions?