It's very simple Tavery and I've just taken the cap off my G3L to show you. The oil filter (Tampon ) slides down its housing tube first, then the steel cup disc with spring on top of it which is compressed by the cap.
The manual says to remove and clean every 2000 miles I'd say it's virtually impossible or at least extremely difficult to do so without removing the saddle.....which means the tank has to come off first. Better to throw the tampon over the fence and just change the oil every 1000 miles. Ron
So sorry Ron. Like I said I have never seen a filter. I thought the filter is open on one end and closed on the other. Anyways thanks a lot for the clarity.