...aka...transparency, as in transparent hose replacing the turbo oil return.
Aquarium variety, 1/2" id. I wouldn't try it with engine at full operating temp, but with oil warm it holds well.
Needs a bit longer length than the stock one, as the angle is steep and it kinks otherwise.
Anyway, the oil flows and you can see it via the odd bubble moving along. I tried it with the crank vent hose on and off.
Interestingly, the oil moved a bit quicker with the hose CONNECTED. So the turbo vacuum from the other side of the camcover DOES help vent the crankcase.
So much for the AET theory about crank pressure blocking the turbo oil return. It doesn't.
So where does that leave us? Dunno really...