As one can see, at the time this photo was taken I was using 100:1 mix Amsoil. I experienced a piston seizure at about fifty-seven and a half flight hours on the engine. It was during a full throttle climb with EGT and CHT temps with in specs. Upon tear down, I discovered carbon under the rings, although the rings were not stuck. Currently I am using Penzoil for air cooled engines at 50:1.