What was found
(CAN) SMOKE/FUMES DETECTED IN FLT COMPARTMENT & CABIN, TOILET SMOKE WARNING ACTIVATED, QRH DRILL ACTIONED, PAN DECLARED, SMOKE CLEARED, RETURN, LANDED SAFELY. MAINT CARRIED OUT AN INSP & CONCLUDED THAT SMOKE/FUMES WERE RELATED TO NR 1 ENGINE HAVING BEEN OVERSERVICED WITH ENGINE OIL, OIL HAS BEEN OBSERVED DRIPPING FROM GANG DRAINS OF ENG & ALSO SOME WETTING OF NR 1 CARBON SEAL (FAN). A/C HAS BEEN FLIGHT TESTED & ODOR OF ENGINE OIL COULD BE DETECTED IN CABIN AND COCKPIT, ESPECIALLY WHEN NR 1 PACK WAS UTILIZED. NO VISIBLE FUMES/SMOKE & NO ALARM TRIGGERED DURING FLIGHT TEST, MAINT PERFORMED A COMPRESSOR WASH & CLEANED NR 1 PACK ECS DUCTING. A/C RETURNED TO SERVICE & HAD NO REOCCURRENCE.