A catch can won't pick up oil that is part of the blow by.
The catch can picks up oil that the oil seperator hasn't been able to get. Blow by is a result of poor piston ring to wall clearance.
have a compression test done to see what cylinders are down on pressure, and have it rebuilt accordingly if needed.
Once you've stopped blowing oil into the chamber and all over your plugs and valves you'll be able to get a better tune cause there won't be any oil in hibiting the combustion process.
Jase