Some Mogs Need axle breather kits, others not. it is a bit of a miracle!
Observe the oil levels and then decide.
You can easily prevent the loss of oil, by means of a hose with a larger cross-section as a vent.
if the diameter is larger than it can bridge the foam bubbles,
they burst and the oil runs back at the edge of the hose.
In addition, some of them have a small expansion vessel
made of gutted gasoline filters looped into the (larger) air vent hose.