FLT CREW OF B727 NEEDS TO RETURN TO DEP ARPT WITH OIL PRESSURE PROB. NEEDED TO DUMP FUEL TO MAX LNDG WT BUT FAILED TO ENSURE ATC UNDERSTOOD SPECIFICALLY. DUMPED FUEL WITHOUT ATC APPROVAL AND MAY HAVE SPRAYED AN ACFT AT A LOWER ALT.

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DEPARTING ZZZ ON RWY 4L. ON CLBOUT TO THE W; THE SO NOTICED THAT THE 3# OIL PRESSURE WAS READING ABOVE THE UPPER RED RADIAL LIMIT (OF 60-62 PSI). ALTHOUGH WITHIN LIMITS; THE #3 OIL TEMP WAS ALSO READING APPROX 15 DEGS HIGHER THAN #1 AND #2 ENGS. FOLLOWING CLEANUP THE QRH WAS REFERENCED AND THE ENG WAS RETARDED TO PLACE THE PRESSURE WITHIN LIMITS. IDLE PWR WAS REQUIRED TO KEEP THE PRESSURE AT 55 PSI. THE ENG WAS LEFT AT IDLE AND ATC WAS NOTIFIED A RETURN TO ZZZ WAS NECESSARY. CHECKLISTS WERE COMPLETED AND LNDG WT WAS CALCULATED. APPROX 10000 LBS OF FUEL DUMP WAS NECESSARY AND ATC WAS NOTIFIED OF THE NEED TO REDUCE GROSS WT. A FUEL DUMP WAS INITIATED. THE DUMP BEGAN AT 10000 FT MSL. THE DUMP WAS TERMINATED AT 5000 FT MSL. THE PRESSURE REMAINED BARELY WITHIN LIMITS AND ENG #3 WAS TREATED AS IF IT WAS INOP BUT LEFT RUNNING. AN EMER WAS DECLARED AND WE RECEIVED RADAR VECTORS TO LAND ON RWY 4L. LNDG WAS UNEVENTFUL AND WE TAXIED TO THE GATE. IN AN EXTREMELY BUSY DEP/ARR AREA ATC WAS VERY HELPFUL AND MANAGED US WITH EXCELLENT SKILL. AFTER LNDG; WE WERE TOLD TO CALL DEP ON THE LAND LINE. POOR USE OF THE PHRASE 'ADJUST GROSS WEIGHT' DID NOT REGISTER WITH THE CTLR THAT WE WERE DUMPING FUEL. AN ACFT BELOW US MAY HAVE BEEN AFFECTED. I HAD USED THE TERM BEFORE IN THE MIL WHEN I NEEDED TO DUMP FUEL AND THOUGHT IT WAS COMMON UNDERSTANDING. THE CTLR STATED IT WAS NOT; SO IN THE FUTURE I WILL USE THE TERMINOLOGY OF 'FUEL DUMP' TO ADVISE ALL AROUND WHAT IS HAPPENING.