A Mooney Ovation2 pilot reported high oil temperatures on initial climb. He declared an emergency and returned to departure airport; where a loose connection to the oil temperature gauge was found.

Narrative

Departed IFR with two passengers aboard. During initial climbout (approximately 2-3 minutes into the flight) I scanned the gauges and noted an abnormally high oil temperature indication (approaching red line). I leveled my altitude to try and get more airflow for several seconds then started a right level turn to the field while advising ATC of the turn to the field. ATC responded for me to turn to the left to a heading of 050 to avoid a departure off a parallel runway. By the ship gauge indication I had an emergency situation and considering it was dark and there was no place to land (should the engine fail) I declared an emergency while continuing the turn; stating I was returning direct to the field.The high oil temperature indication stayed just below red line and I was cleared to land. Landing was uneventful. I cleared the taxiway and shut down the aircraft (for possibility of fire) and we exited the aircraft. The Fire Department and airport employees were present as we exited the aircraft. I called the FBO and requested they send a tug to our location for a tow back to their facility. We removed the top cowling in the hangar to see if there was something obvious. Nothing appeared out of order. I traced the wires from the oil temp probe to the connection to the ship gauge (under cowling) and checked them for security. The connection could have been slightly loose and upon moving it and moving the tie-wrap around it and seeing no other anomalies; and reviewing the incident step by step; all indications were that the connection was suspect. No maintenance was performed; only a thorough inspection to confirm the aircraft was airworthy. Note: The alternate JPI engine monitor did not alarm at any point in the flight which would have occurred if the reading on the ship gauge was accurate.The above was accomplished while conferring with a Mechanic on site and two by phone; all were in agreement it was most likely a poor connection (EGT; CHT; and oil pressure were normal for the phase of flight). I did a thorough run up to confirm the two oil temperatures matched and they did within 1-3 degrees (the range was well within normal). Being confident the issue was resolved I did a flight (second run-up) as the sole passenger in the Class C airspace. All was normal. The flight was re-filed (a third normal run-up accomplished) and completed without incident. My Mechanic removed the heat shrink at the suspect location and found a connection that could have been better. He reworked the connection and made a log entry.