A few years ago some SCCA rotary road racers had discovered the lower
the oil temp the more the power. It did not dawn on me
why that was necessarily true until I read the SAE paper I just up loaded.

Here is the reason. The volumetric eff. of the engine is being
affected by the temperature of the face of the  rotor which in
turn is being cooled by the oil.

Keep the oil hot during cruise for best BSFC and cool for max power.

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A 6% improvement in the BSFC would drop the BSFC from the current
.47 to about .44 which is about the same as a Lycoming.

The typical cruise fuel burn would go from about 10 GPH to about 9.4 GPH.

Easy to do. Just put a cowl flap on the oil cooler air outlet.
Not only will that warm the oil during cruise it will cut the
aerodynamic drag. This has pertinence  in endurance road racing as
well as aircraft.

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Come to think of it this is also why the rotary BSFC is so much
better at higher power levels compared to what it is in a car piston engine.
Mazda needs to find a way to turn off the rotor oil cooling squirter's under
typical low power car cruise. In other words they need to find a way to get more
heat in the rotors at 4,000 RPM at the 30 and 40 HP power levels typical of 80 MPH
cruise. I would not be a bit surprised if this did not increase the EPA highway
numbers by one or two MPG.