Oil pumping out fill tube

[Druck1]

If the oil level in the sump is low, exposing the fill tube port, will oil get pushed up the fill tube, (and then through the vent tube into the vent box.)?
That seems to be case after some 4K-5K rpm driving with low oil.
Tower vent and fill tube vent into a high mounted EMPI box. Rocker vents blocked.
Thought I would check before over thinking this. Hope the answer is proper oil level

[Clatter]

Would need more detail and maybe a pic or two of your breather setup..

Low oil level shouldn’t cause it to start moving the oil out the breather.
That would be catastrophic for the manufacturer.

[Ol'fogasaurus]

If the oil level in the sump is low, exposing the fill tube port, will oil get pushed up the fill tube, (and then through the vent tube into the vent box.)?
That seems to be case after some 4K-5K rpm driving with low oil.
Tower vent and fill tube vent into a high mounted EMPI box. Rocker vents blocked.
Thought I would check before over thinking this. Hope the answer is proper oil level

Just a guess here but it is sounding like you might have a basic venting problem where at higher RPMs the engine is pushing more air than it can vent; e.g., with no place for it to get out of the engine. Exposing the fill tube port is the only quick option for the inanimate engine.

So if true, then this is not a new engine problem but something like it used to happen in older engines when the straight out vent itself got clogged. The vents often used to be attached to the oil fill tube and if the exit part of the fill tube got clogged then the pressure from inside the engine used the fill part of the tube by popping/blowing off the press-fit vent/fill cap allowing the pressure to escape dragging along oil suspended in the air at higher RPMs.

Just a thought. Lee