Hope you feel better now, Stan. BTY , my car has a dry sump system so maybe I'm # 4 in your list.
My number two Son, Jesse felt the ire of the dropping screw for the first time in his life while helping me with the Soob Frankenmotor install in the Speedster. The oil filler tube is fixed onto the top of the right side valve cover by two small screws. While making sure he had the right screw he dropped it right down into the valve train. A probe magnet found nothing available and nothing was in sight. He said " I'll get it just leave me alone". I took the BSA out for a short run after telling my Wife not to bother Jesse in the garage. I came back about 1/2 hour later and the bugger is sitting with his feet up having a cold one in the garage and smiling. He couldn't pull it up and out so he loosened the two valve cover screws, pulled the valve cover out a bit ( there's about 1/4" clearance to the frame rail otherwise you pull the engine to get the covers off ) , found the screw and pulled it out the bottom. I let him ride the BSA that day.
Also, if one carries 12 litres of oil instead of four or five would that imply that oil change frequencies would decrease in proportion ?