That watch is very kewl. Sinn Has oil filled watches, never seen one. Apparently Most are Quartz Movements, since the oil requires the watch hands to generate more torque. I have seen some youtubers oil fill casio's as well. Nice Find!
Here is My Grail Watch, it is oil filled as well and mechanical:
https://ressencewatches.com/pages/type-3
It was my understanding that only quartz watches could be oil filled. The viscosity of even thin oil would have to effect the operation of a flywheel. I’m interested to know how Ressence pulled that off.