Mechanical Fan VS Electric Fan

T for sure. Brings engine to proper functional levels.
I think 180 is prob right, we are running a 160 high flow in the 440. It has factory elec fans / shroud and we had to mod them to run full time to keep the car reasonably cool and added the 160 T stat during the mod.
This "up to temp" allows the oil to flow properly rather than being too thick to provide proper pressure / volume in critical places and flow to the top end for that upper end type of oiling. Secondly temperature makes the tolerances proper. Thirdly temperature vaporizes pollutants in the oil and transmission such as fuel, water, and mysterious dissolved and suspended aromatic crap. The third benefit of proper operating temperature improves trans fluid and engine oil longevity considerably and eliminates damage caused by the pollutants because they "burn off".

I very much believe an up to temp non "pure drag" engine runs more efficiently both on power and fuel economy. The intake charge needs to be cooled but not the engine too much.

My rambling opinion :)

Hey, Plumcrazy, what is the application? What is your build and use?