First- Thanks up front for your answers on this question. It's been an issue for me but am learning to live with it. I have a pair of CAT 3208 Naturals (non-turbo) in my '78 33' SF that both consistently run at 142 F. I've replaced the thermostats with new ones and the temp is the same...142 F. The engines don't smoke (white, black or grey) and run beautifully. Does anyone else have CAT 3208 Naturals that run less than the prescribed 180 F? I've not put an infrared temp gun to them or attached any other sort of exterior or aux thermo's. Anyone else out there who may have the same issue?