What was found
THE VALVE SHEARED AND MOST OF IT DEPARTED THROUGH THE EXHAUST, LEAVING ONLY PART OF THE KEEPERS AND FRAGMENTS OF THE TOP OF THE VALVE WITHIN THE ROCKER BOX COVER. THE ENSUING VIBRATION LED THE PILOT TO BELIEVE THAT HE HAD A CATASTROPHIC FAILURE AND THE ACFT WAS CRASHED ON AN ABANDONED FIELD. THE EXTENSIVE DAMAGE LED TO DECLARE IT A TOTAL LOSS - ONLY 1 AILERON SURVIVED THE CRASH, EVERYTHING ELSE WAS BENT OR CUT. IT IS HARD TO DETERMINE A PROBABLE CAUSE, THE OIL WE ARE USING, WHICH INCLUDES MFG ADDITIVE. ALSO, PUT 1/4 OF AVBLEND OIL TREATMENT ON EVERY OIL CHANGE.