[madmaxx]

Thermostat just opens and a predetermined temperature, if you car will overheat with a 195 thermostat it will overheat with a 160 F thermostat, it will just take 5 minutes longer. Performance unlimited has an excellent write-up and corresponding graph. The problem with running below 180f is the cylinder walls stay cool but the pistons reach temperature and voila, excess cylinder wear wall. The optimium temp is 200F but the increased life between 180F and 200F is nominal.