Gentlemen,
Keep in mind, a thermostat's purpose is to maintain a MINIMUM coolant temperature. If you have a heat problem, a colder thermostat will not resolve it.
For
oil to properly due it's job, it must maintain enough heat to keep some impurities burnt off, and provide optimum protection from metal to metal friction. Granted, if a short engine life is acceptable, colder temps can be run. I would avoid any temp less than 180F for coolant, and a minimum of 200F for
oil. Heat is not always the enemy it's made out to be, unless excessive, of course. Excessive cold temps can be far more damaging, especially in the long term.
Regards,
Dave