The Oil Temperature Sensor threads into the forward top of the oil pump. It is a Bosch part. The threads are metric (M12 X 1.5).
The Performance Electronics part number is 50040002. The cost is $30.
The connector is the basic EV1. $6.50 with pigtail.
The signal line for the Oil Temperature Sensor is M08.
The ground line comes from a splice off of M26.
Tom Habrzyk advises that the temperature sensor has no specific polarity so can be wired either way. Since my pigtails had red and black wire, and since I’d been following the basic rule that red means power and black means ground, I found no reason to confuse myself by switching things around.
Junk Yard Zetec 