I have exhaust only on the belly.  I did have one oil leak that was at the rear of the engine for 300 hours.   No amount of cleaning could track the source.   Recently, I changed the starter adapter and found studs that needed repair and the leak was from the bottom of the adapter.  With that now repaired, I have zero drops on the hangar floor and zero oil on the belly.  I have no separator.  I keep the level around 7.   I have a factory new 550TT engine.  Hope that helps as a data point.