My 2013 R56S with 6-speed manual has never used oil between its 5k-mile oil changes. Suddenly, at 75k miles, it used one quart of oil in about two weeks (didn't notice how many miles I'd driven). At the same time, I experienced some clutch slippage between 3,000 and 3,500 RPM when accelerating moderately.

This clutch only has 35k miles on it, as the rear main seal started leaking at 40k, and both it and the clutch were replaced at that time by the dealership. And BTW, this is my daily driver which I drive sensibly -- no full-throttle takeoffs from a standing start, etc.

It seems likely to me that the rear main seal is leaking again, causing oil to get into the clutch assembly. However, upon first inspection (without taking anything apart yet), the mechanic says he sees no evidence of an oil leak, but does recommend replacing the clutch again due to the slippage.

What are your thoughts? There doesn't seem to be oil coming out the exhaust, but what else could cause the sudden oil consumption? Could a bad PCV valve do this? And is it just too much of a coincidence to have both problems pop up at the same time to dismiss the possibility of a leaking rear main seal?

 

There should be a weep hole at the seam between the engine and transmission. There is one on the gen 1 MINIs anyway. So if the rear main seal is leaking you'll see oil there and likely on the ground under your mini.

 

I don't know the details yet, except that the mechanic(s) didn't see anything before removing the transaxle. That was supposed to happen today (April 5), but I haven't heard anything yet.

Still wondering what else could cause the sudden onset of oil consumption.

 

Heads up on the front and rear crankshaft seals. These are PTFE seals, and they have very specific installation instructions. The dealership may have installed the seal incorrectly.

Specifically:

1. Seals must be installed dry (if you put oil on them, they will leak immediately.
2. After installation, you can't start the engine for 4 hours; the seal has to normalize to the crankshaft
3. Special seal driver tools are used to install, and they aren't cheap!

 

No leakage was found -- anywhere! So that means the oil is being consumed somehow. My service advisor just brushed off my suggestion of replacing the PCV valve, telling me that I needed to let the engine warm up for 5-10 minutes before driving. What a load of B. S.! So I'm going to do the PCV valve myself. It can't hurt anything.

As to why the clutch lining was down to 1mm with only 35k miles on it, I don't know. Maybe it was installed incorrectly? I definitely do not drag race the car.