[Released] Wing42 Boeing 247D

Well the ability of radials to convert oil to blue smoke (and splatter anything left over everything in sight) , rapidly and efficiently, is renowned !

Though that works out at something like a pint every 4 minutes which does seem a lot.

Temperatures below 180 °F (80 °C) are problematic as it is not hot enough to burn off water in the oil.

Temperatures above 225 °F (105 °C) in air cooled engines are also problematic.

I am not sure of the recommended range for these engines but it is going to be somewhere in the 85°C to 100°C range I suspect. Your 80-90° range sounds correct for °C.