i am looking at buying a 2000 audi A6. it ran and drove great but when it warmed up i smelled what smelled like oil burning.when i opened hood it was smoking from passenger side of engine.i didn't get to look too close but my first thought was valve cover gasket or exhaust manifold gasket. is there a problem that is common to this car that this could be?

 

it may just be the valve cover leaking which isnt unheard of, worst case scenario would be blown head gasket but if you can see smoke more than not its just a leaky valve cover gasket, let the car cool down see if theres any oil, if not start the car and see where it starts to smoke from or if any oil leaks out.

 

Langl, yes, this is very common issue with this vintage Audi, use the search feature.
I had the same oil smell, smoke from back of engine on passenger side, and also thought it was VC gasket. It can also be the cam seals, cam tensioner seals which are at the back of the head below the vc. These are a known to leak as built-up pressure in the cylinder head forces oil past these seals and it burns on the exhaust manifold causing the smell/ smoke. One cause can be a plugged up suction pump, a Y-shaped plastic adapter part of the PCV system, it's at the back of the head near the firewall.
There are lots of better explanations on this forum, use the search feature. Good luck