To be honest, if the return was blocked you'd have no flow at all and the oil would soon overheat I would guess.
Even if the oil return were blocked I'd expect the leak to be internal through the bearing seals, so the oil would end up in the intake and be burned, or the exhaust and be burned.
Could the oil be coming from somewhere else? For example a dirveshaft seal and be sprayed upwards. Alternatively, I don't know what the feed / return pipework is like for the oil. Could the leak be from this?
I have to agree, no matter what, the PCV
is a quick and free place to start as these are known to cause oil problems with the turbo if the crankcase ends up pressurised.