Oil in Exhaust

[J R Briggs]

Have been battling this situation for a while. 
After vehicle is warm there is blue smoke at idle and more expelled when beginning acceleration.
Have 210M miles on this 200 20V and owned it for 22 years - babied it probably too much. In AZ now so rubber and plastic dries pretty easily.
Anyway my Audi guy (who was actually working the AUDI factory in the Germany the year this was built) says just drive it it is old and tired, but really hasn’t come out of his office to get to the real source of the problem.
Says it could be turbo, or valve guides, or rings and probably not worth inching into an engine re-build.

So I took it to someone else and took a look at the turbo intake to see a little oil and saw none on the exhaust side of the turbo.
Pulled the plugs and saw some carbon on top of select cylinders, so maybe it could be rings.
Checked with additional resources and got this feedback:
Thought that valve guides would produce blue smoke at initial start up due to leaking overnight but this has not been the case and learned it may not be the case either.

This source did not think it would be rings.
Source thought perhaps the turbo pressure regulator might be the source of the problem but if not to look at the valve guide.
We are going to take it on step at a time staring with the turbo pressure regulator.

But I wanted to query thoughts from this audifans great knowledge base that has helped me work through things over the years.

Thoughts?
Comments?
Germany
Jim B in AZ