A thermostat sets the MINIMUM operating temperature of the engine. If the coolant temp rises much above the thermostat setting in normal operation (not pulling heavy loads uphill, or other high stress situations) you either don't have enough radiator, or the radiator and/or the engine water jacket is dirty. Last weekend, I towed a heavily loaded trailer over several mountain passes- - - - -the temp gauge on my tow vehicle never moved above the bottom third of the gauge range. No, it wasn't a stovebolt, but it has a clean, properly designed cooling system.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!