Agreed, Forced Induction....Agreed....

But I still find it interesting why Dad's 617.952, which logged 194,000 miles with no thermostat at all, had such minimal cylinder/skirt wear that it could have been re-ringed back to standard.

Here in Visalia, the summer temps are well over 100°F and when I was working at the dealer, we put the 60°C thermostat in everything, since either one could be easily obtained. We never had a complaint about a reduction in fuel economy or a power loss either.

Since both a 60°C and 85°C thermostat is available, I would suggest the 'correct' device is the one that gives you the most satisfactory heater performance, based on your climatic conditions...Robert