If you are talking about DOF, are we talking about this system?
https://www.youtube.com/watch?v=5xnVaMjaxGk
Some thoughts on that.
Every oil circuit has an oil filter bypass. So the oil is not filtered under all circumstances.
The IMS bearing material wasn't designed for an motor oil feed. Is was designed for a special grease filling.
But hey, maybe i think too much sometimes.
Regards, Markus