16 hp briggs and stratton engine pushing oil into crankcase breather tube. The engine is in a Cub Cadet 582 and the oil collects in the air cleaner pan. The oil level is correct. Any idea what might be wrong?
Thanks in advance for your help.

Replace the breather assy.

You could have a crankshaft seal leaking,or it could be bad piston oil rings.
You need to have manometer to test the internal pressure of the engine.
Good Luck

DG:

Can you explain this "manometer test", the range in pressure/vacuum and at least one piece of equipment capable of doing the job?

It's a simple instrument.Theres several sights that show them .the one I have I made.

Lots of time what causes oil in the breather on briggs engine.is a simple leak around the dipstick tube where it goes into the engine

Culprit is most likely the "Breather Valve".
Follow the hose from the air cleaner to where it attaches to the engine and that is where the breather valve is.

You will have to remove the air cleaner & intake manifold to get to it.

When you take the breather off there should be a steel flapper.
See if it moves easily, if it doesn't, try spraying some carb cleaner and see if that frees it up.

Also check for damage to the flapper and check the gaskets.

I have a herd of these 14.5 hp I/C engines and every couple of years I will have to do this to at least one of them.

I am going to experiment with an automotive PCV valves where the oil breather hose comes onto the air cleaner and see if any of these will work, because it is a major pain to tear so much stuff off to fix a simple problem.

The thing is when you have that BIG 500cc piston moving back and forth you get some very high crankcase pressures.

That sounds like a plan. Try looking a 3 or 4 cylinder engine cars or the PCV for the gasoline engine in a Hybrid car.