Couple thoughts on this. From previous years of v-twins I have never had one that does not throw a little oil in the filter especially at high rpm. Most just collect and is easily wiped out. Some gets on filter which probably helps collect dirt. Mine drips a few drips on lifter cover if I let it set a few weeks and then drive it hard. (oil tends to run down and collect when bike is left setting) Had an 05 few years back that had a drain hose on the bottom of the box. I really think Harley only intended for the actual mist to be drawn into the engine. Putting the actually pipes back into the throttle body probably is not a real good thing since oil does not really burn in a liquid form until it get on the hot exhaust valve and stem area. Just a thought for thinking and of course debating. Not trying to steal thoner7's post...

 

I had oil dripping out of my AC and dribbling down the side of the motor and pooling on top of the side cover and blowing backward on everything all the time. It finally stopped when I let the oil level drop to anywhere between the bottom mark on the DS or about 1/4" below it and kept it there. I also put on one of those finned aluminum permanent oil filters which is supposed to draw off some heat from the oil to compensate for the slightly lower oil level in the tank.

 

Pretty much like CHarley and others, 2.5qt brings my '05 1200C to halfway between fill and full marks. The manual says anything over the fill line is fine. Mine uses / pukes no oil & hasn't in 31k miles.