Hello, I would think that section of the oil filter housing has, "already filtered" oil going to the turbo. You would'nt want to risk getting flakes of metal going to your turbo bearings.

I am pretty sure that on some oil filter towers...there is a plate that bolts to the back of the filter tower that is removeable. That removeable plate contains the threads that your turbo oil feed line hooks to via a banjo fitting...as well as the oil pressure sending unit just above it. It is hard to determine the removeable plate bolts since that area (on my engines anyways) is caked over with old oil deposits. Clean the area with a toothbrush and some sort of degreaser...and you will be able to tell for sure what I am talking about.

You could just get a new gasket and another used plate with good threads and replace it. Just four bolts.

I don't know for sure, but maybe Mercedes sells new plates and you can order one with your new gasket for that said plate. Maybe a new banjo fitting and two new crush washers too if it is cross-threaded. I think the oil line itself is very expensive if you need a new one. Some guys have built their own to save money.

Some of the more experienced guys will weigh in on your issue soon enough. Maybe wait for their response as I am no expert.

There is also a thread on here somewhere, that touches on the importance of the turbo oil feed line itself being attached in a couple of spots to the engine to avoid the line cracking due to vibration. Hopefully someone can attach it for you. I don't know how to do that.

As I was typing a response two others had already addressed your issue with a picture of the plate...sorry to repeat as I am a slow typer.