A CRJ-200 diverted to a nearby VMC airport following receipt of a left engine low oil pressure indication shortly after takeoff from an airport with minimum RVR readings.

Narrative

During climb out at about 5000 ft; we received a LH ENG LOW OIL PRESS warning message. The oil pressure indication was fluctuating between 20 and 45 psi. We complied with the QRH for Low Oil Pressure and once we put the affected engine at idle the oil pressure remained at 30-35psi. Oil temperature indication always remained in the normal range (at about 90 degrees C with the engine at idle). Because of these two reasons we decided to keep the engine running at idle. We were complying with an MEL which required us to keep the landing gear down for 10 minutes after take off. However; seeing that the BTMS [Brake Temperature Monitoring System] indications were close to 1 and 2 units we decided to retract it to increase our single engine performance. Our departure airport at take off time was reporting RVR2000 and for this reason we decided to divert to a nearby airport with VMC weather and longer runways. Just to be on the safe side we declared an emergency with ATC. We briefed the Flight Attendant and the passengers on the situation and accomplished the single engine landing QRH; and landed without further inconvenience. Mechanics said that about 5-6 quarts of oil were missing from the engine.