2 bar oil into the gearbox

Hello have a question, and a buddy told me that he fills normal 2-stroke oil into the gearbox in his Simson. And with his Hercules Moped always emptied unmixed 2-stroke oil into the gearbox. He says he has no problems with the clutch or any other. Now my question is whether it is good or if you prefer to fill in SAE80???? MFG Michael