Dash 8-100
Flight Crew Last 90 Days 180; Flight Crew Total 3500; Flight Crew Type 2500
Aircraft Equipment Problem Critical
Flight Crew Rejected Takeoff; Flight Crew Returned To Gate; General Maintenance Action
Aircraft
The #2 Engine Oil Pressure warning light illuminated at 80 KIAS during the takeoff roll. This resulted in a rejected takeoff.  This primarily involved myself and the captain taking corrective action.  The flight attendant and the passengers were informed and briefed before returning to the gate.The event occurred after reaching normal takeoff power; and was found; by a mechanic; to be due to a low oil quantity on the #2 engine. No leaks were found.The Tower was still closed.  We had previously de-iced with Type I fluid due to frost on the aircraft.  After lining up on runway I held the brakes for 10 seconds at 40% torque.  After releasing the brakes; it was a normal power takeoff with power promptly reaching 90%.I was the Second In Commend (SIC) and I was also the pilot flying.  At approximately 80 KIAS the #2 Engine Oil Pressure warning light illuminated.  The captain called to reject the takeoff and assumed control of the aircraft.I broadcast to the CTAF that we were rejecting our takeoff and clearing the runway following the rejected takeoff after noting the indicated airspeed.  We stopped on the taxiway to evaluate our systems.  We notified Center on the ground through a remote antenna to cancel our IFR release.  We notified operations that we would be returning to the gate; and I made an announcement to the passengers that we were returning to the gate due to an abnormal indication during takeoff and that for safety precautions we were calling maintenance.I then called the flight attendant to assure that the passengers were okay and then briefed the flight attendant on the plan to return to the gate and to deplane the passengers while we waited for maintenance.Careful and timely attention to oil consumption and oil leaks should lead to a mitigation of issues like this.
Dash 8 First Officer (FO) reported observing a #2 engine low oil pressure light at 80 kts on the takeoff roll; leading to a rejected takeoff.