What was found
AIRCRAFT LEFT THE AIRPORT WITHOUT A PREHEAT AND TEMPS IN THE 20'S DEGREE FAHRENEIT. SHORTLY AFTER TAKEOFF, ENGINE STARTED SMOKING, AIRCRAFT RETURNED SAFELY TO THE AIRPORT. CAUSE OF THE PROBLEM WAS FROZEN MOISTURE IN THE OIL SEPARATOR WHICH DID NOT ALLOW CASE PRESSURE TO BE RELIEVED THROUGH THE BREATHER LINE. CESSNA DOES NOT USE ANY METHOD OF BYPASS ON THIS AIRCRAFT SHOULD THE BREATHER LINE EVER BECOME PLUGGED SUCH AS THIS EXAMPLE.