How do I drop my highway temp 8°?

[Vegas69]

A high flow t-stat may be a good compromise to none. If the coolant temp is 150, oil temp could be 150-170. Far from ideal. The moisture won’t burn off very efficiently and your oil pump will work harder. That can lead to distributor gear wear and failure. Lubrication is typically superior with reasonable oil temps. No stat will lead to a long warm up cycle too. A reasonably light synthetic would be my choice if you try it.

No stat in the summer is another option. I can see the benefit of the flow assuming the radiator can take advantage of the extra volume.