The gauge is pegged all way to the right. At times it will return to normal range after restarting the engine. Any ideas appreciated.
Probably uses a thermister as the temp sender. The circuit will have a 12v feed into the gauge, the thermister is the ground for the circuit. As the oil heats up, the resistance of the thermister drops and allows more electricity to flow, which causes the needle to head for the red zone. More than likely you have an intermittent short in the wire between the gauge and the sender. The current goes to ground, just like a sender with low or no resistance. Thermisters are weird ducks in that the resistance drops when heated. Just about everything else needs to be cooled to lower the resistance. Think super cooled conductors and magnets and the weird things they do.
Have you located the sensor? If so take the wire off and see what the gauge does. If this does nothing take the ground wire off at the gauge and see what happens. Bad sensor, bad gauge, or intermittent short in the wiring... ?
Check your gauge connection as well. Your may have the old three wire plug on the gauge side. Just reseat it. I would check your wire where it goes through the floor for a rub.
Thanks everyone for the info.