Damned if I never considered this. I'm 14 years retired from a Colorado state vehicle emissions testing laboratory. This was not a state inspection site but rather research lab. I was licensed to perform and issue valid inspection certificates, however this was done only when lab testing problem vehicles. Anyhow, I suspect that since the high octane fuels are supposed to burn slightly slower, perhaps more heat could be sent into the cylinder walls. Makes sense to me. The level of heat tranfer may be somewhat small, but that issue was never tested in our lab during my time there. Still, makes sense.
