As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT OBSERVED FLUCTUATING OIL PSI (100-70PSI) BROUGHT POWER BACK TO 200 LBS. TQ AND OIL PSI DROPPED TO 50 PSI. PILOT FEATHERED AND SHUTDOWN EFFECTED ENGINE. AFTER MECH INVESTIGATED THE PROBLEM, FOUND THAT FUEL HAD MIXED WITH THE OIL SUPPLY AND DILUTED IT TO A WATER LIKE CONSISTENCY. BELIEVE THAT THE FUEL OIL HEATER CORE HAS HOLE IN IT WHICH WOULD ALLOW FUEL TO MIX WITH THE ENGINE OIL SUPPLY. (K)