cause of heavy breathing

[jimbob-mcgrew]

what things can cause an engine to breath heavy, and throw oil out the breather hose ?

[meritlover]

Worn rings/bores/pistons, a penetration between the firing ring and an oil return, the rear or top breather choked.

[mowgli]

Also too much oil, oil in need of changing, breather filter gummed up so it won't let it drain back.