This is normally not due to "leaking seals" inside the turbo charger
Problem & Solution
Common among these chassis:
If you see a lot of wet oil in the compressor housing and on the compressor wheel of your turbo charger, it is most likely not coming from inside the turbo (unless your turbo is totally worn out with damaged shafts and bearing surfaces). The oil you are seeing is due to excessive crank case pressure which is caused by worn piston rings and cylinder walls. This excess pressure inside the crank case forces engine oil by the pistons as well as out through the breather and into the intake - then it enters the turbo as a very fine mist. The way you can really confirm this is do the following. After a long fast run (30 minutes over 60 mph) pull the big elbow off that connects the air filter and the turbo. If the inside of the plastic elbow is wet with oil you have too much “blow by.”
This excess oil does not mean your engine does not have more life left, but you will not be able to fix the “oil in the intake” issue without overhauling the engine. Many diesel engines will go a few hundred thousand miles with excessive blow by. You just have to deal with things like higher oil consumption, oil in the intake, and possible oil leaks due to the crank case pressure.
When will you know if your engine is REALLY worn out. When it won’t start on a cold morning and you know your glow plugs are working properly.