Normally for reasons of manufacturing economy (greater tolerances) there is some need to have the space between the tip of the moving vane and the stator cylinder too large for only an oil film to seal.
For example in the standard linear piston engine the space between the moving piston and the static cylinder wall is filled with several thin rings. These rings do essentially scrape the wall of the static cylinder except for a very thin film of oil. We call these rings "piston rings."
In principle one could avoid the use of these rings. Just make this space between moving piston and static cylinder wall very small (high tolerance - exact control of the piston size and cylinder size - their diameters) but that is too costly for mass production, so "piston rings" are used.
What I was suggesting with your vane is that it be spring loaded to keep the tip of the vane very close to the cylinder wall to reduce the cost of very high tolerance manufacturing.
I assume you know about standard linear motion piston rings, but will mention that they too are springs. I.e. They are not continuous rings, but have a small gap open in their circumference. This gap needs to be reduced, compressed, when they are inserted into the cylinder so they naturally expand to essentially scrape the cylinder wall.
SUMMARY: I was suggesting the exact length of your vane is not constant. That it has an internal spring trying to make it longer than the radius of the static cylinder so that it always (even after wear) is essentially in contact with the cylinder wall - only a very thin film of oil away. This is very much like the use of piston rings in a linear motion piston. It is done to reduce the cost of manufacture. I.e. the bore and piston diameters do not need to be made with very high precision as the piston rings fill the "tolerance gap"
Your vane could have very slight ability to lengthen or contract so your manufacturing costs could be lower too.