What was found
LEFT ENGINE OIL PRESS CWP ON THAN OFF IN FLIGHT, LEFT ENGINE OIL PRESSURE NORMAL, LEFT PROP OIL PRESSURE FLUX RAPIDLY. PERFORMED QRH, EXAUSTED LEFT PROP. NORMAL OPS. RETURNED TO DTW. MAINTENANCE REPLACED LEFT PROP OIL PRESS/TEMP INDICATOR. OIL LEVEL CHECKS GOOD, RAN AIRCRAFT AND ALL CHECKS GOOD.