Besides race bikes I've built, ran lean, hoping they'll go 30 laps or so, I've never siezed a street bike from the wrong mixture. It's always been a mechanical failure (or a better description would be cheap chinese manufacture failures.) Blown main bearings, losing the ring keeper on the piston, rods stretching just enough to slam it into the spark plug, or other parts disintegrating, not from lack of oil or over heating. Race bikes, different story. Bumping up the hp to it's threshold and beyond, running max rpms non stop, over revving and slipping the clutch til it screams, that kills 'em. Started running racing oils with castor sauce in them at around 16:1, and they stopped overheating. Still blew up when the aforementioned cheap internals failed, but not from lack of oil. Plus it made a good, stinky, smokescreen for the poor guys behind me.