heh. My first engine was the pro 15, dads was the 2.5, my second was the 2.5. His might've run forever because he always ran it super-soaker rich. Still doesnt explain the severe dirt damage i found in it. (top layer of chrome plating completely removed from one part of the sleeve, with the nickel exposed...)
It was worse then my pro .15, but still ran, and he even used an air filter all the time.
Ok, well, no chunks were missing out of the piston like the pro .15...