I have a small coolant loss, about a pint every 1000 miles; heat works fine, car stays cool even below the MIN mark on the reservoir. Had had a cracked thermostat housing replaced (that was a larger coolant loss) but even so the leak continues. Brought it to shop where the thermo was done, they put it on a pressure tester for 45 minutes, NO LOSS IN PRESSURE! What gives? Stuart Friedman