Engine Running too Cool?

The purpose of the thermostat is not to keep the engine cool, it's to get the engine up operating temperature quickly, and to keep it there.

I read once that 95 percent of engine wear occurs before an engine reaches operating temperature. And that is why it's not uncommon for NTC taxis to get 1 million plus miles, they are constantly at operating temp, and therefore not causing much engine wear.

Another consideration is wether the oil is getting hot enough to burn off the moisture in the oil.

I run a 195 degree thermostat in my 72, and even in an Austin summer where the highs are usually 100+, I never have an issue with overheating.