My 2012 GL350 with 87,000 miles has the original oil separator. Is there any reason to proactively replace the oil separator wuth a new part at about $180?

I have read Mercedes has updated the part many times, but last time at the dealer when I was talking with the tech he indicated there was no reason to replace it. Without the hoses failing how can you know if replacement is necessary?

 

If it fails internally, lots of oil will get transmitted with the blow-by gases (It has a diaphragm inside to regulate at what pressure it allows passage).

Usually, when it fails things start getting greasy. Things like any/all intake hose connections especially the ones before the turbocharger.
(And, the ones after the turbocharger!)

If you get the big leak at the turbo inlet, hot oil may be dripping on the intake flap actuator motor which can then fail too, from melting.

There are aftermarket replacement parts available for this, I know Vaico makes them, plus probably more.
Another discussion of the issue:
https://mbworld.org/forums/gl-class-...-question.html