In my 1927 Flyer gearbox I use Millers SAE 40 monograde oil. This oil has only little additives and is designed for use in older engines. I use the same oil for lubrication of the engine (fed by a modern, throttle controled oilpump). I never drain the reservoirs/wells.
Just to be sure I use a 1:50 mix in the petrol. For that I use a normal, mineral two stroke oil.
My Scott does on this setting not really smoke.
Erik
