I recently changed my oil and i noticed it was leaking oil from a circle with what looks like a cap over it. Everyday i have been checking it and a amount of oil has been leaking from it. It's on the left side where you put the oil in back area. I'm not sure if its a gasket or something more serious??? If anyone could give me some advice on what might be the problem that would be great.

 

You have a 96 A6? Not sure how different it is from my 98 but on mine, the cam plugs were leaking. They look like caps just like what you described and there's one at the back of each head.

Not too hard to replace. The caps are like $2 a piece IIRC. Use a pick tool or screwdriver to pierce a whole in the top of the cap, then work it out.