Although I never overheated (except for one stuck thermostat) in the 36 years I've owned mine, I now recall that a few times when stuck in long traffic jams in 90+ weather, I shut off the AC and turn on the heater to add another radiator to the system. Don't know if it was necessary but it was just an ounce of prevention. People pay a lot for a dry sauna.

I guess that having just an idiot light kept my paranoia about temp in check. It must not ever been too much for the engine since it's never been worked on in 37 years and 178,000 miles.