Matt,

With reference to the idling before setting off issue, and the piston feet per minute, I am assuming that the higher compression, the higher BMEP, all things else being equal, the greater ring and cylinder wall wear?

That, if true, might mean that the new Mazdas with their "Skyactiv" technology with 14 to 1 compression will wear out sooner. There is the factor as well, that I have read that engines last far longer with fuel injection due to the excessively rich condition with carbs when cold. Like, about twice as much mileage on a engine before it is worn out.

Looking at the factor that friction increases as the square of RPM, it would also make sense that operating at low RPM would add engine longevity as well, assuming that the friction increase at least is partly located in the piston-cylinder interface and will result in increased wear. Hard to see where if there is no friction, that any wear at all will occur.

Not anything I have measured, to be sure. I have been an advocate for setting out immediately with a cold engine, not asking more than the minimum until there's an indication on the temperature gauge, or on my Toyota, when the green "cold engine" light goes out. I've never worn out an engine in my life. Oops, those chain saws I lunched due to using on-hand outboard oil in the fuel mix, I wore them out. How easy it is to believe I am smarter than the company engineers. And to find out the hard way they were right. It took two chain saws before the light came on. You have to use 2-stroke oil rated for "air cooled engines", at least my experience has bought me that knowledge.

Thanks for sharing your hard-won knowledge with us. It's really interesting.

Carey