Best possible mileage?

Duggie said

That's interesting on engine temp. After repairing everything wrong on the engine and cooling system and keeping it factory spec, once the thermostat opened the engine temp never changed much on any driving condition. The temp gauge is just a graphic without numbers, but the needle is up there when the 195 degree stat opens. The needle hasn't moved hardly at all once the 195 deg stat opens. So far...

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To be clear, I haven’t had an issue with overheating or boil over. With a 180, the needle is real close to the overheating side of the gauge, and we were testing it in summer time. Driving around the city it would creep up slightly at stops and then drop back down to “normal” when I drove around again and the fan was moving.
With the 160, the needle sits just inside of the cool side of up-to-temp on the gauge. Similar situation. When driving, no issue. 3-hours on the interstate and the thermostat didn’t show any warmer than normal. Sit in traffic for 5-10 minutes and it starts getting toasty and temps steadily rise.
I suspect the issue stems from the mechanical fan or lack of shroud. With a shroud I think it would do a better job at idle since it could pull across the entire profile.