Hi guys! I'm a new member and about 3 weeks ago I purchased a Laser Blue 2008 Cooper S with a 6 speed. I had the oil changed on it this past Friday. Previously, it was running 5W-30 and now it's running 0W-40. The same shop did the pre-purchase inspection on the car and I've been told there's a small oil leak from the valve cover that is dripping onto the exhaust manifold. Before the oil change, I hadn't noticed any blue fog from the leak. After the oil change, there is blue fog upon startup and while driving too. What really has me confused is that the smoke is coming from the tailpipes and there is oil residue on the exhaust tips. The shop says that this kind of valve cover oil leak causes the smoke from the exhaust but I don't understand why oil that's outside of the exhaust ends up in the exhaust and out the tailpipes. On a side note, I had the breather tube replaced because it had a hole in it that was throwing a check engine light. I appreciate all the help I can get on this one.

Before I forget, here's my car:

 

Perform a Leak Down Test as I suspect a valve seal. Could be caused by carbon buildup or a seal that is worn out on the exhaust end. The valve cover is just that, a cover. There is a reason oil is getting into the exhaust end of the system and I can’t imagine the cover is allowing that much oil to leak through.

 

Same problem with mine. Blue smoke decrease with thicker oil. Can be valve seal or piston rings

 

So it's been a couple weeks or so and the smoke has stopped. I think it was overfilled on oil. I bet the shop filled it with 5 quarts instead of 4.6 like Mini suggests.