A B757-200 flight crew noticed low oil pressure on the #1 engine. All other parameters were normal; and after consulting with Dispatch and Maintenance; they declared an emergency; and diverted to the nearest suitable airport while operating the engine at idle thrust.

Narrative

While level at FL 370; we noticed a flickering #1 engine low oil pressure light; accompanied by the loss of #1 engine oil quantity. The oil pressure was within limits; the engine was operating and producing equal thrust with the #2 engine. No abnormalities could be seen visually from the cabin; nor were there any abnormal vibrations from either engine. We advised ATC of our problem and requested a lower altitude. As a precaution I reduced the left engine thrust to idle. We reviewed the appropriate procedure; and had it standing by if the situation deteriorated further. We contacted Dispatch who conferenced with Maintenance. After lengthy consultation with Maintenance and my crew; I made the decision to leave the left engine at idle until after landing; assuming all parameters were within limits. Maintenance concurred with this decision. After adequate discussion of landing fields; we decided ZZZ would be our safest course of action. Utilizing Captain's Authority; I declared an emergency with ATC and requested direct routing to ZZZ airport. Given the wind conditions; we requested and were cleared to land on [Runway XXL]. Prior to landing we reviewed all single engine procedures as a precaution. The landing was uneventful; and we shut down the left engine after landing. Emergency vehicles inspected our aircraft; with particular attention to the left engine; and gave us the all clear. They followed us to our gate at which time we canceled the emergency.