Adding an in-line diagram canister would result in It getting just as sluggish once it was packed full of oil.
Is this proven, or just theory- I ask because the diaphragm fluid/vacuum separation method exists in the automotive world in many applications. The only functional issue appears to occur when the diaphragm gets old and tears. Until that point, the oil really doesn't go far up the tube- with the system sealed, there is no vent to allow fluid flow.
One such application I have come upon was my 1994 Ford Explorer. There is a vacuum modulator line that runs from the intake manifold down to the transmission. Only after my diaphragm tore, did fluid in the line present itself. Just food for thought.
Once my test mule is ready to go, I will be testing this concept by way of a fitting installed in my governor arm hole. If it doesn't work out, you'll be the first to hear about it...
EDIT- I have just come to the embarrassing realization that when I was commenting on the EGR system earlier, I was thinking of the PCV system- ironically, the original topic of this thread...



