In the diagram, if you have a wee peep at the hose where number twelve is and where the hose goes into the main air to turbo intake. This is where the engine crank case vapour arrives and then goes on into your turbo........all along the line will be sucking in an oil mist. This will coat the turbo etc in oil.
I have mine blocked off, and as an aside the crankcase vapour hose breathes elsewhere into another hose which in turn breaths into the inside of my chassis.
Anyhow, if you take your air turbo hose off and rub your finger around it there'll be oil. This in turn is why you'll need to rinse out your intercooler ( Land Rover had a part number for a cleaning product back in the day) and you'll also find your intake manifold coated in oil.
The pictures I took today show my turbo intake as clean and along with the inlet manifold. An engine without blocking off will have a thick layer of oil and grease which the engine will ingest as time goes by. It's an easy fix and will make the engine last a good bit longer. A catch can can be installed if need be. My turbo has about 650,000kms on it.
I trust this helps somewhat.
All the best.