Anthony;105249 wrotePhilia_Bear;105196 wrotePan is easy
Yes but there is a risk that if the turbo oil drain end point is below the normal sump oil level, then the drain won't flow properly and will back-up.
Meaning fresh clean oil to the turbo bearings / sleeves will be restricted and result in a shortened life.
If doing a pan oil return, the pipe must be as high as possible. And a lower sump oil level is recommended.
No it does not work like that
If the oil cant flow freely out of the drain it will just bypass the rings on the front and the rear of the shaft and start flowing into the housings this only takes 2psi of pressure for this to happen
Even if you have a good drain and there is more tha 2psi of crankcase pressure the oil will still bypass the rings and do wonderfull things in the housings (importance of a solid pcv system noted here)
It would need to build up pressure over 20psi to stop flowing through the turbo and that would mean that the entire block would need to be at 20psi at which point every rubber seal on the engine would have blown out
Also as oil flows into the turbo you have an equal amount flowing out of the pan and creating space for the oil to flow back into the pan