Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Aircraft Equipment Problem Less Severe
Flight Crew Landed As Precaution
Aircraft; Environment - Non Weather Related
Dispatched on a Ferry Flight Aircraft X; from ZZZ to ZZZ1. The aircraft had not been flown in a long time. Departed ZZZ with 18.5 qts on #2 and 18 qts on #1. My FO was new on the Aircraft and restricted. We departed ZZZ uneventfully and all indications were very normal till well into cruise. We both noticed during our checks that the #1 Engine Oil quantity was decreasing with all other indications being normal and no vibrations present. The Oil quantity would decrease then increase. That pattern continued on the descent into ZZZ1. I advised Approach Control of the situation and we were given vectors to a short final ILS XXL. On final the oil quantity indicated below 4 qts to 3.5. I requested priority handling. With a new FO I took the airplane and landed uneventfully Runway XXL at ZZZ1. Oil quantity increased back to 7.5 qts during taxi in.I was called the night before and given a heads up that the plane had not flown in a long time. Maintenance; my FO; and myself all did extremely thorough walk-around and internal inspection of the entire cabin. We were well prepared for this ferry flight. These type of Maintenance items/events seem to happen to planes that sit for extended periods of time.I believe these planes should not sit for extended periods if that can be avoided somehow.
Air carrier Captain reported the oil quantity fluctuated during a flight on an aircraft that had been stationary for a long time.