Columbia 400 instructor pilot reported returning to departure airport after noting high oil temperature indications.

Narrative

While acting as Flight Instructor for student's Instrument Proficiency Check (IPC) in student owned Columbia 400 aircraft; we departed VFR with intentions of practice approaches NW of the departure airport. After departure checklist and while level under the Class B shelf; I noticed a high oil temperature indication on the Multi-function Flight Display (MFD); indicating an oil temperature pegged out on the 250 deg. F scale. I alerted the pilot flying and he reduced throttle settings; resulting in the temperature falling to 230; then returning to 250 degrees F. I alerted the Pilot Flying that we needed to return to the field and directed him to begin a turn direct to ZZZ. I contacted Tower; but was unable to get through on the Tower XXX.X frequency. Another emergency aircraft was reported inbound and we were the second inbound aircraft requiring priority. I was able to contact Tower on YYY.Y and we were informed of the other emergency inbound and instructed that we were only going to be given priority by declaring. I opted to agree that we [required assistance] as well and was informed by the Controller they [would provide assistance] for us. I continued with the radios while the pilot flying was able to enter a right downwind for runway XXL. We were cleared to land XXL and were able to land uneventfully.During the remainder of the flight; the oil temperature fluctuated from being pegged at 250 deg. F down to below the green arc of the indicator all the way into the 140 deg. F region. Our oil pressure remained in the green (approximately 45psi); but our number 2 EGT dropped off of the scale entirely on the MFD. After landing; I inspected the aircraft and saw no evidence of an oil leak and the engine was indicating full oil on the dipstick. The aircraft is going in for maintenance on the field for further investigation. We were not given a phone number or required to file any report due to the priority given by ATC.