N57/435D Oil Leak - Common causes and places to look?

[brentrentatent]

Hi everyone.

Having an issue with my 435D, 50500 miles.

Firstly on iDrive it says oil is full, plenty of power and not smoking at all. No oil in the intake either.

I noticed subtle dripping on the driveway recently, upon further inspection I noticed the undertray was saturated with oil when looking from the bottom and when you look from the top there is quite a lot, especially on the intake/drivers side.

I did a bit of research and came across the common oil filter gasket, and as this is an easy place to check I did so, nothing running down the block etc on that end so I assume it is not the oil filter gasket.

For those who have more experience with these engines, any idea what this could be? I had thought maybe turbo bearings (can't see that happening at 50k miles anyway) but car doesn't smoke at all nor is there oil on the air intakes side when I took that apart.

I have tried googling but it seems unknown oil leaks on the N57 is quite rare and can't get much information about it.

I want to first try and diagnose this lot myself and see if it would be an easy fix before I have to pay the £250 excess on my BMW insured warranty.

I'd just want to know if there are any common fault Ares where I could perhaps look...

Also, I have ruled out transmission or transfer case fluid as I double checked the colour of the fluid with a paper towel and it is indeed black engine oil.

Any advice would be great thanks!

At this stage I am wondering if I shouldn't cut my losses and buy something else the minute I can afford it...

Are these N57 engines generally problematic or am I just unlucky?

Cheers in advance