Mark

We verified oil temperature bulb resistance readings for a reference to indicated temps.

Sitting static on a warm day we found 100Ω to be 30 degrees.

We didn't know the range that the bulb might have. The first try at 200Ω was invalid. We found just a sight change in resistance would make the indication change. A 5Ω increase in resistance gave use a 10 degree rise in indication. I would imagine full scale hot/cold would be a pretty tight range of resistance (let's guess 80Ω to 120Ω)??