What was found
DURING CRUISE, NR 4 ENGINE OIL TEMP INDICATION INCREASED TO 140 DEGREES CELSIUS. ENGINE OIL PRESSURE AND ALL OTHER ENGINE PARAMETERS REMAINED NORMAL. ENGINE THRUST WAS INCREASED TO MAX CRUISE AND OIL TEMP REMAINED HIGH. ENGINE THRUST WAS REDUCED TO IDLE AND OIL TEMP REMAINED HIGH. ENGINE WAS SHUTDOWN AND THEN RESTARTED 10 MINUTES LATER, WHEN THE OIL TEMP SUDDENLY DROPPED TO 75 DEGREES CELSIUS. OIL TEMP INDICATION WAS NORMAL FOR REMAINDER OF FLIGHT. REPLACED NR 4 ENGINE OIL TEMP SENSOR IAW DC8 MM, CHAPTER 79. ENGINE WAS GROUND RUN AND OPS CHECK WAS GOOD.