[Ruth]

Running too cold is bad for an engine as the byproducts (unburned H/C, water, and acids) of combustion will condense in the crankcase and not vent out the breather to the atmosphere. These byproducts will promote corrosion in the crankcase.

I run a 160°F thermostat. On a hot day with the thermostat wide open my engine runs at 170°F. The addition of a thermostat will not cause an engine to run hot at some seem to believe.