Excessive Blow-by from the wearing of the rings or valve guides? The more miles an engine accumulates, the more Blow-by gasses & oil gets into the PCV system, past the guides & rings. Some Engines like my LS 6 & all first gen LS engines, are just prone to it, regardless of miles. That's why I put in a catch can. IMHO , a quality CC can help. Even rigging up an old type paper gas filter & or an air compressor water separator inline with the PCV hose to the intake will help.