What was found
(CAN)IN CRUISE PILOT NOTICED OIL STREAMING BACK ALONG CANOPY. AN EMERG WAS DECLARED & ACFT LANDED.ENG WAS SHUTDOWN IMMEDIATELY & ACFT TOWED TO MAINT.THE OIL LEVEL PRIOR TO FLT WAS 6 QUARTS AFTER ENG SHUTDWN THE OIL LEVEL WAS CHECKED AT 3.5 QUARTS.POST FLT INSP FOUND THE FRONT CRANKSHAFT SEAL WAS POPPED OUT OF THE CRANKCASE.THE PROPELLER WAS REMOVED FOR INVESTIGATION & NO DEFECTS WERE FOUND.THE ENGINE OIL FILTER & SCREENS SHOWED NO DEFECTS.CRANKSHAFT SEAL WAS INSPECTED & FOUND SERVICEABLE.SEAL REINSTALLED.ENGINE BREATHER LINES LAGGED.IT IS SUSPECTED THAT THE ENG BREATHER LINES FROZE & THE CRANKCASE PRESSURIZED & THE SEAL POPPED OUT.ACFT RETURNED TO SERVICE.