[chilehed]

I'd like to point out that excessive crankcase vacuum generally won't cause excessive oil consumption...

Yes, except insofar as the excessive vacuum might be indicating excessive flow through the ventilation system, so that the ability of the system to separate the liquid and gas phases is overwhelmed. That's why it's important to have the right orifice installed.

 

[chilehed]

What orifice where?

The check valves function as orifices to limit flow. If the valve is too big...