As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 4 ENGINE OIL PRESSURE BEGAN FLUXUATING IN CRUISE AND THEN WENT TO '0' PSI. NO LOW OIL PRESSURE LIGHT CAME ON. ALL OTHER ENG PARAMETERS NORMAL. SECURED NR 4 ENGINE AT 0340Z. REMOVED AND REPLACED ENGINE OIL STRAINER. NO CONTAMINATES NOTED. REPLACED MAIN ENGINE OIL FILTER IAW DC-8 MM 79-20-07. REPLACED OIL PRESSURE TRANSMITTER IAW DC-8 MM 79-32-01. PERFORMED ENGINE RUN. NO FLUXATION NOTED. SYSTEM LEAK CHECKED GOOD.