Here is the official response from Kymco:
John,
In this case, the service manual is incorrect. The correct volume of gear
oil for this unit is .21 liters at disassembly, and .181 liters at change.
Even with the low volumes described in the service manual, the unit should
operate properly with no abnormal side effects. This is due to the
technology and exacting tolerances used in the design and production of
these parts; these systems only need a small amount of oil for lubrication
and rely very little on the oil for cooling purposes as older designs did.
Steven Oliver
KYMCO USA