01 A6 2.7L Turbo. Aggravating leak!
 

The passengers side is burning oil. White smoke and nasty smell are getting old fast. I thought it was the valve cover so I replaced the seal. Did NOT stop. Any other ideas on what it is?

And I'm considering a stop leak. Anybody have experience with them? I have heard they do more harm then good.

I would recommend against stop leak. It's tempting to just put something in the crank case and be done with it, but it's not a good idea as it will begin to restrict flow and generally clog things up.

The valve covers are tricky to get on the first shot. If you only did the inner and outer valve cover gaskets I would also suspect a leaking cam cap from behind the head. This is a pain in the ass to get to, but it's doable without taking much apart.

With the engine warm to cold, reach behind the passenger side head (right around the kombi valve) and feel for a circular piece of plastic with pegs in it. Once located, follow it down with your fingers and see if there is oil leaking below where it sits. If there is (And most likely this is the case) then you need to replace it.

Had the same issue and it was the CAM seal like Nebuchadnezzar mentioned. When performing one, the dealer mentioned that the other needs to be replaced. I did have another (non-Audi) mechanic mention, that it is not necessary if it isn't leaking.

Here's sketch of rear of engine showing the cam caps. FYI, it's possible you may also be leaking oil from the seals at valve covers &/or seals at cam chain tensioner (camshaft adjutment valve N205 in pic). These can leak oil down onto your exhaust manifold, along with down the backside of engine.

You need to replace the rear cam plugs along with both timing chain tensioner seals & gaskets.

Try this. When you do your cam cover gaskets, 1) clean all the surfaces very well, 2) use new gaskets, 3) use Black RTV on the lower corners of the head, both sides of the gasket and on the cam cover. Use it sparingly and spread it along the surface about 6 inches horizontally and about 1 inch upwardly if that makes sense. Assemble. NOW listen. DO NOT start the engine for at least 24 hours. Allow the Black RTV to cure properly. You will not have any more oil leaks. Period. If you start the engine before the Black RTV is cured you will get to do it all over. Lots of posters here will disagree but what do you have to lose at this point. Your oil leaks, that's what! :p

And as long as your in there do the half moons and tensioner gaskets. Easy.

What about the leaky cam plugs & tensioner gasket & seal? They start leaking when the valve covers gaskets start leaking. They are made from the same material.

Yes, for sure do those. I believe I covered that in my final sentence. :D

17 is my my leak and I'm going to change the timing chain at the same time since the car has 100k miles on it.

Attachment 17285

Timing belt? You leak, #17, is a half moon seal. Do the whole shebang as long as your that far into it. Tensioner seal, cam cover gasket etc.