What degree Thermostat?

I found when I installed an oil temperature gauge that an engine is only a"warmed up" when the oil reaches operating temperature (which takes longer than heating the coolant). Cylinder head temperature is probably an even better indicator.

I know when drag racing, my best E.T.'s were achieved after the second and subsequent runs, when the engine was completely warmed up but had sat in the staging lanes waiting for 20 to 30 minutes. I assumed the coolant had cooled off some during the wait in line, but the oil and engine parts were still good and warm.