My son's 2007 MCS (67k) is guxxlinhg oil - a quart every 200-300 miles. There is no visible oil leak; no loss of power and no blue smoke.

My trusty Compression tester does not fit this vehicle so I await delivery of a compression tester and leak down tester - probably tomorrow.

In the meantime I have pulled the plugs - I think I have attached photos of them?? They do not look like pugs from a major oil burner - perhaps I am wrong.

I'd really like some other opinions on this. Oh yeah, and I inspected two large orifices on the driver side of the turbo. There was a very small drop of oil - half the size of a dime - i think in from of the impeller. I could be mistaken as to which orifice. Again - did not seem enough to account for the oil loss.

Anyway - first step prior to compression and leak down is to see if anyone else has a better eye on the photos I tried to attach to this posting - thanks!

also - I believe these plugs have been in the car for quite a while - can's say for sure

 

OK - Compression test completed

All four cylinders were between 150 an 152 PSI. Its good that this is even but are they too low?

 

I should add that this reading was taken cold. Once it stops raining I will retest warm.

 

Last time a dealer checked my compression they noted "All cylinders are within 5% of each other and between 160-180PSI. Checked OK". This was done Nov 2010 on my '07 MCS. I doubt seriously that a 150 - 152 CR is gonna burn that much oil. And when it's tested hot, there should be slightly better readings.

When you say "no visible oil leak" do you mean no puddles on the ground, or no oil residue on the engine, or both?

There's a chance that the turbo is leaking oil into the compressor housing (exhaust) --- not getting burned, just collecting in your exhaust pipe. Your oil droplet in the turbo inlet could come from the PCV tube --- is the inlet hose dry, with no oil residue? Could also come from the turbo center section --- crankcase pressure not allowing turbo oil to drain. Or just a bad turbo seal / bearings --- does the turbo shaft have any free play --- side-to-side, up-down, or in-out? Shouldn't have any free play.

Three of your plugs look kinda rough. I'd be concerned about why the fourth one is so clean looking. Might just be time for a new set --- won't help your oil problem but should improve performance.

 

Oldbrokenwind - I am honored to have you respond. In the few weeks I have been on this site I have seen so many useful posts from you. Thank you.

In answer to your questions:
1.No visible leak mean I looked everywhere - no signs of leakage. With this volume I'm sure it would be apparent.
2. I have come to the same conclusions that you have. (1) turbo or 2 (PCV related issue.

I have ordered a turbo rebuild kit and oil lines as that looks relatively easy (relative in Mini terms) to do; inexpensive and will extend the turbo life at the least.

I will wait until I see the results before attacking the PCV system. I will check the hoses as you suggest.

The spark plugs are already on order

thanks again - I will report back as I learn more.

 

If the oil is coming from the turbo, a rebuild kit needs to contain at least a replacement CHRA (Center Housing Rotating Assembly). Considering the age but low mileage, the wastegate is probably due for replacement, but it's part of the turbine housing, not a separate item. If the car is to be kept for a few more years, you might have been better off replacing the entire turbo.

Anyhow, best of luck, and keep us posted.

 

Partial update. I have not yet been able to perform a leak down test because the car needs a 10 point tuner lug nut bit and the seller did not provide one - as I have learned

In the interim I filled the oil to the maximum allowable on the dipstick frown about 30 miles and it is down to the minimum marking. This is crazy. I think I could remove the piston rings and burn less!!!!!

Amazon brings me the tool on Thursday and I have Friday scheduled for the test.

I see no oil in the coolant and no the 1/4 season of oil at the bottom of the turbo compressed air output line.

I am thinking the following in order of likelihood until I test further:

1. Oil seal in turbo - I should not that the car came with the advice the turbo needed to be replaced. I read the code and it indicated that the by-pass valve was failing (it intermittently put of the half engine signal but would quickly go away) I have not yet installed the DV+ i purchased)

2. Bad valve cover PCV system

3. Valve seals and, perhaps, guides

4. Rings or valves - although at 150 compression across the board this level of oil consumption seems unlikely.

Any thoughts are welcome - I will advise when I know more.

I should add that I was aware the Mini is a synonym for what they do to your bank account so no alligator tears for me!!!

 

Wow that a lot of oil to burn, and you don't see it coming from the tail pipe? You don't actually have an oil leak?

My first guess would be the valve cover/pcv failure, but that's a pricey part to replace without any confirmation.

 

not blowing blue smoke - looks a little like a rich mixture at idle, 40 degrees f. Even if I couldn't find an oil leak I presume one of the following: (1) I would have enough oil on my driveway to open a refinery (Ha) or (2) I would smell the unmistakable aroma of oil burning on a manifold or exhaust pipe.

I am really perplexed. If it is the turbo oil seal(there is no play in the impeller shaft), and It is not percolating through to the intake side of the equation, then how do I check for oil going into the exhaust manifold? Or, perhaps, into the intercooler?

I' really stumped given the 150 lbs of compression!

 

Oh yeah - one more thing to add to the mystery. When I registered the car under a month ago it had to be CA smogged. It passed without issue. If it was burning a tanker of oil, could that be possible?

 

I think you are losing oil either through the PCV system or the turbo seals. It could also be a leaking valve guide. If it is getting burned up in the engine and going out the exhaust, the catalytic converter will take care of it, for a while anyway until the cat is too fouled and stops working. I have a Subaru that is doing the same thing, and it passed CA smog a few months ago too.

Checking the PCV and turbo seals should be straightforward, lots of threads about oil loss through both paths.

 

Do a visual inspection of the turbo exhaust outlet --- either disconnect the downpipe from the turbo, or remove the top O2 sensor and use a borescope. You're looking for oil residue, not just damp spots, but puddles or obvious signs of liquid --- un-burned oil. Maybe also take the exhaust pipe apart somewhere between the downpipe and muffler --- let us know how wet it is in there --- like un-burned oil? Are the O2 sensors wet, or just dirty?

If oil was being burned in the combustion chamber, you'd probably fail the smog check. Oil being cooked in the exhaust pipe is more likely to pass the test, and as mentioned earlier, the cat will be ruined.

I'd really like to blame the turbo seal, altho 3 of the 4 plugs look like they've been burning more oil than gas, which implies other problems. Let us know the results of the suggested tests when and if you do them.