A slightly unofficial - but official - line here. When I attended the RHC safety course there was a discussion on oil consumption started by owners on the course. What emerged was that when the Raven II was introduced there was no new oil level or dipstick introduced with it. The reason was a bit mumbled and unclear. But I definitely heard a well known RHC person tell us that the Raven II prefers to be run with its oil level closer to the lower limit on the stick.
Tried it - it's true. Anything over 8 qts just gets blown out.
In fact if you look in the Lycoming IO540 handbook that comes with the Raven II, you'll see that the acceptable oil level is a lot lower than 7 qts.
Anyone know if the STC'd oil catch tank/recirculater has made it outside the USA yet ? It's a third party item - and the guy I heard about in the States claims that he never needs to add any oil between checks.