What was found
AFTER TAKEOFF AT ABOUT FL 200, INCREASED TEMP ON ALL THREE TEMP SELECTORS AND COCKPIT FILLED WITH SMOKE. TURNED THE TEMP SELECTORS TO FULL COLD AND RAN THE SMOKE, FIRE, AND FUMES CHECKLIST IN THE QRH. THE SMOKE DISIPATED. RAN ALL THREE ENGINES, UNABLE TO DUPLICATE FAULT. ISOLATING ENGINES AND PACKS. INSPECTED PACK COLESER BAGS, FOUND OIL LEAKING IN NR 3 PACK.