A B757 engine lost all oil quantity and the pressure was low but Maintenance suggested leaving the engine running since other indications were normal. An emergency was declared and the flight continued to a divert airport with the engine at idle thrust.

Narrative

The Captain requested a phone patch with a Maintenance Engine Controller. Once the patch was set up; the Captain described low oil pressure on engine number one as well as zero indicated oil quantity. Maintenance advised that it sounded like a possible leak but as long as adequate pressure and temperature was still being maintained; no inflight shutdown was required immediately. The Captain agreed to pull the throttle back to idle thrust and I prepared some METARs and TAFS for the nearest suitable diversion airports. The aircraft was between two suitable airports but both airports were experiencing low IFR ceilings of around 300 FT overcast with both forecast to go lower as the day progressed. The low IFR conditions were prevalent throughout the eastern plains to the south and north as well. The Captain indicated that he was not comfortable with those ceilings and forecasts. A suitable airport was available to the east and was VFR but the Captain was most comfortable diverting to a much larger airport which was also VFR but provided longer runways for the one engine landing. An emergency was declared by the Captain and we agreed upon the divert station. The aircraft landed underweight on the runway with Airport Rescue and Fire Fighting equipment standing without incident.