I think they might be using an oil pan or
oil sump on the turbo. We and other have had a lot
of trouble with oil drain back from turbo's. Particularly
if they are mounted low relative to the engine main oil pan.
Chuck Hurburt went so far as to to add an electric
scavenge pump to the turbo as I recall.

I also see a line going into the Porsche turbo oil pan that might
be a vacuum line. A bit of vacuum down here would help
scavenge the oil vapor from the turbo.