air filter

Just wondering if anyone has converted the air filter system to a standard paper filter?

The oil system seems to work ok but I've never seen this before and don't know if its a good way to go. Any recommendation on the type of oil for the air filter and how often to change?

Thanks for the help.

The air filter is not only an air filter but also a noise trap.
I would not advice you to put a paper filter on this motor.
ACMA advised the Vespa 400 owners to clean the filter and put new fresh oil every 10.000Km.
I use a good gearbox oil for this.