A perfectly running engine will put atomized oil into the air within the crankcase. Every engine has some amount of ring blow by and this excess air introduced into the case must be equalized/expelled. The air with the atomized oil suspended in it gets exhausted out the breather to equalize the excess pressure from the blow by and over time the atomized oil will stick to surfaces that air comes in contact with.
Years ago you used to see streaks of oil in the center of the road. This stopped when the EPA mandated PCV systems to prevent those vapors from entering the atmosphere. The OEM went to closed / recirc systems.
You want an air oil separator to reduce the oil left on the belly.
As bob mentioned, running to high of an oil level increases the cavitaion caused by the crank and this dramatically increases the amount of atomized oil created and why they blow out oil rapidly until the level is below the crank.
Placement of the hose won't change the amount of air and oil coming out of the engine.
Lycomings recommended fill level is not to accomodate what the engine needs, but instead to meet a standard for how much oil can be lost/consumed in a specific amount of run time without dropping below the minimum required, which is usually 2 quarts or less. If your consumptrion rates are above 1 qt in 10 hours, there is simply no need to put 8 quarts in a 4 cylinder engine.
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress
Last edited by lr172 : 02-28-2019 at 10:49 PM.