JUST AFTER MAKING THE INITIAL TAKEOFF CLIMB POWER REDUCTION THE PILOT NOTICED THAT THE ENGINE OIL PRESSURE WAS INDICATING ZERO. BEFORE HE COULD LAND AT HIS DEPARTURE AIRPORT THE ENGINE SEIZED. AN OFF AIRPORT FORCED LANDING RESULTED IN SUBSTANTIAL DAMAGE TO THE AIRPLANE. THE ENGINE OIL FILTER ADAPTER HAD SEPARATED FROM THE OIL PUMP HOUSING, AND ALL ENGINE OIL WAS LOST. THE THREADS ON THE ADAPTER AND HOUSING WERE WORN AND DAMAGED. THE ADAPTER HAD LAST BEEN INSTALLED USING WATER PUMP PLIERS INSTEAD OF THE SPECIAL WRENCH AS PER THE CESSNA MAINTENANCE MANUAL.