What was found
AT CRUISE, FL380, THE LEFT ENGINE OIL INDICATED ZERO, FOLLOWED BY LOW OIL PRESSURE. CONDUCTED A PRECAUTIONARY SHUTDOWN OF THE ENGINE IAW QRH. SINGLE ENGINE TIME WAS 42 MINUTES. DECLARED AN EMERGENCY. THE AIRCRAFT WAS GROUNDED. REPLACED STARTER VALVE IAW AMM 80-11-03, REPLACE STARTER, AND STARTER SHAFT IAW AMM 80-11-01-400. ACCOMPLISH AMM 71-00-00-210-802-F00, REPLACED THE NR 1 ENGINE STARTER QUADRING ADAPTER, AND CHECKED FOR DEBRIS IAW 11-02-400. ACCOMPLISHED ALL STEPS OF MIC 70357514. LEAK CHECKED AND ENGINE TEST CHECKED SATISFACTORY.