One of those curly ears broke off one of the wrist pin retainers. Had nothing to do with the oil. Kinda weird though.
Just finished rebuilding a shelf queen Stihl 034 that ate one of its wrist pin retainers. The piston took the brunt of damage and the otherwise immaculate cylinder was scored below the intake port.
Before this incident I liked the wrist pin retainers with the "ears" as they are easier to install and remove, but I've had a change in heart.