[Lake Effect]

So, it's been a while...
I bought the 2017 M2 used with 30K miles on it, I've only managed to drive it another 12K since then, covid restrictions turned me into a recluse because I just didn't want to deal with the people...

Finally started driving it regularly again about a year ago, noticed an oil drip on the garage floor, not a lot, and I assumed I had a small leak at the drain plug.

I was wrong, I found oil on all of the rearward oil pan bolts, and some also coming down the front of the engine.

In an effort to avoid becoming a BMW mechanic, I have enough obsessions already, I took it to a very popular local "European Car Repair" shop that regularly has nicer cars than mine, and ones that are a bit more common.

They diagnosed the oil pan gasket and Oil Filter housing (orings), which was no surprise, and replaced them for $3,200... That was a tough pill to swallow, but it was my decision, and I really didn't want to deal with that pan gasket without a lift.

Got the car back, two days later, a lot more oil on the floor...

Take it back, diagnosis is the oil pan gasket might be leaking at the rear, they'll replace it again at no charge. After putting dye in the oil and doing a lot of driving and checking for leak sources (2 days of effort from a mechanic who seemed to know her stuff, they believe it's the turbo oil line (pressurized side) leaking, and while they are in there, they'd like to replace the coolant lines and orings as well, another $3500... They also haven't ruled out the rear main seal.

I approved the pan gasket and guess I'm going to have to sort out the rest myself if it's still leaking, because I'm starting to have trust issues.

Question for the trained and DIY mechanics who've been into the turbo area. I'm assuming the turbo oil drain/return line goes directly to the oil pan, how likely is it the oil pan efforts tweaked the presumably hard lines feeding and returning oil from the turbo?

I'm not going to challenge the shop, I just want a good idea of might be the real cause before I start turning wrenches.

I'm having a hard time believing that every orifice of a 42K engine starts bleeding within a few weeks. It's not like the car sat still for the covid eternity. It was my happy place taking me for groceries and regular testing (I travel every other week for work, and the airlines as well as customs people were pretty thorough) so it's not neglect from disuse.

I'm open to feedback, I'm in a long term relationship with this car, and knew that eventually I'd get my hands dirty. I just didn't think it would be so soon

[captain slowly]

I'm gonna go ahead and say the shop might be a bit lost on this one. The rear main seal should have been done during the oil pan gasket repair. From what I understand, the PCV goes bad, and when it does it takes out the rear main seal. Do you hear a slight whistle at idle? If you do, it needs a PCV which is a part of the valve cover (at least in the S55 but the N55 should be the same). You need to take the car to the dealer, or a shop that really knows BMWs

[Lake Effect]

Thanks for the insight. I haven't noticed a PCV whistle, but, I'll pay closer attention today.

[tx_M2]

Seems like they have no clue where it's coming from. They are throwing parts at it at your expense. I'm sure they want to replace everything they can. Get that car to a dealership or you will be 10 grand lighter in the wallet fast.

[booya_45]

Or at least take it to a shop that is familiar with that platform (f87).

[Lake Effect]

Thanks again, I'll be bringing it home today and will keep track of the new state of the leaks, hopefully it was really just a pinched oil pan gasket and it's fixed.
Of course there is no way to tell if they did the gasket a second time, but I'll be happy to have it back either way.

I'm currently learning VW diesels, swapping into other vehicles. I wanted to avoid learning this platform for a while, just because of time management constraints, but deep down I knew going in that trusting someone else to turn wrenches would be a problem.

I'm not even upset with the shop. They cater to a different type of owner. This area has a lot of 'money is no concern' people, I've just reinforced for myself that I'm not one of them, and I'm happier knowing a job is done right and then washing the oil off my hands.

[E90convert]

Sounds like the PCV system got clogged and is pressurizing the crankcase causing the leaks. Replacing the valve cover is the fix if this is the case. Well documented on N54 engines, and even my N55 335i had this happen at around 50k miles.

[Lake Effect]

So... finally have a real answer...
Headgasket external oil leak under boost.

With the car on the lift and a boroscope camera, we were able to confirm the valve cover gasket is clean.
We also could see the oil seep location at the head/block interface, passenger side.
We agreed the oil pan gasket was probably never leaking, couldn't agree the oil filter housing probably wasn't leaking.

Shop manager reached out to all of the other shops (they have 5 or 6 locations) plus some of the other more respected independents to see if anyone else local has seen the same problem. Answer was no, not in this engine...

Advice from the shop manager was to go to the dealer, let them diagnose it, and try to get BMW to cover it out of warranty (timed out).

I'm okay with this, it is what it is.... and maybe they'll just say it's the PCV system and handle it....