As far as the oil temp that is for transmission temp. Unless you are loading alot and stalling the converter it will register low most of the time. You engine temp problem could bad a bad thermostat, sender,gauge or wiring problem. Take the wire off of the sender and the gauge should read cold, ground the wire and the gauge should go to hot. If it does work like this then it is the thermostat or the sender. If it doesnt than the problem is in the gauge or the wiring. Also the gauges are replacable as individual gauges and also you can get the printed circuit separatly.