Where's My Oil Going?
 

I bought this R56 Cooper S (N14) that had jumped time a little. I replaced the timing chain and found timing chain guide debris covering most of the oil pickup. IIRC, I checked the compression, and all was fine. After this and a bunch of other work (including replacing faulty O2 sensors, which might be important), I've put a couple thousand miles on the car, and it runs fine. But it consumes very roughly a quart of oil every 200 miles, which is far more than I read is common elsewhere on this forum.

As far as I can tell, the car does not smoke. I believe I have noticed a bit of oil/soot on the back of the car after long trips. I have oil on both sides of the intercooler and a little in the intercooler. It's not a lot. Maybe a couple tablespoons. It seems like there's more of an oily coating closer to the engine's air intake. There were no oil leaks after my repairs, and there's only a minor leak now, probably from the valve cover. I don't believe there's any oil in the PCV system or upstream of the turbo.

My hunch is that the turbo is toast - some o-ring or something. The car has around 113k miles, and it was not well kept. I'd like to rebuild the turbo or, at worst, replace it. I don't want to have to keep traveling with tons of extra oil on board, and I don't want to foul cats and O2 sensors with oil. But is this where my oil is going? Is the turbo the culprit, or could it still be rings or something?

Thanks in advance!

The PCV system in the valve cover is a prime suspect, see the Gen2 FAQ on N14 engine maintenance.

I suspect that if that were the case, I'd be seeing oil in the intake upstream of the turbo?

There are two paths for oil to exit the valve cover, one through the hose that connects to the intake before the turbo, and also internal ports that lead to each of the intake ports. The N14 engine was notorious for needing carbon buildup on the intake valves cleaned due to oil from the PCV system going through those ports and coating the back of the valves. There's an updated version of the valve cover available that does a much better job of condensing the oil vapor and getting it back to the crankcase. Also with age, the internal rubber diaphragms in the valve cover PCV system are known to fail. Do a search, there's lots of information about it.

Because you have oil at the intercooler, If there's oil at the turbo intake then it is the PCV system for sure. If not then the oil at the intercooler is likely from the turbo bearings. But that doesn't rule out oil going through the internal passages to the intake ports as well. Usually such high oil consumption is the PCV system in the valve cover.

Good luck and let us know what you find.

Update: I changed the turbocharger. I haven't driven enough to check on oil consumption yet, but the car has a lot more power than it had before. I'm hopeful the oil issue is resolved too.

Hope you solved it - keep us posted!

As stated above if the valve cover has not been changed it should be as PVC valve is part of cover.

Updated valve cover n14
 

I presume part no. 11127646555 is the updated valve cover? I ask because I have similar oil issues (and there's oil everywhere in the intake, from the pre-turbo pcv hose to the valves). Does it really makes that much of a difference?

I had broken valves from all that oil I replaced the cover & spray sea foam into air intake back of the cover with engine running then shut engine off for twenty minutes or so!

You didn't mention what model & year, assuming you have the N14 engine that appears to be the correct part. Check realoem.com to be sure for your specific model and year.

Yeah, that's the latest revision. Is there any way to tell what's on my car by looking at the part - any moulded-in part numbers or such?

My valve cover is a tiny bit melted around the bolt nearest to the turbo. I figure as long as I'm sure there's no hot exhaust leaking onto it, I might as well replace the valve cover with the newest version and give the intake valves a good walnut blasting.

I found that after replacing all the things mentioned above that the main reason I was leaking oil was due to valve steam seals.

I can see that resulting in burning oil, but not leaking oil (the valve stem seals are inside the valve cover).