I learn my dealer used synthetic oil in my A6. I have never hired people to change my oil or do other repairs, but in the terms of the warranty they would service it at some rather large intervals; 10K as I recall. I don't want to wait that long for service and will do some myself.

What are you using for oil?

 

Mobil 1 is the best; I use 0w-40, Up theirs and the 10K miles. I'm changing mine 3-4K which is a little more than twice a year for me. Do the filter every time too you can get them at Audi or sometimes I use Pure One. My engines already look cleaner inside the valve covers. I also try to use Shell premium, I'm not sure if it helps but my cars run good on it.

I bought my cars used and I know at least one was dealer serviced. The sludge under the valve cover wasn't pretty but it's going away now.

 

I think that the interval is the most important thing and this depends on your driving conditions. More highway - longer interval. More stop and go or short trips - shorter interval.

Use good oil. I've been using Castrol GTX 10-40 in the winter and 20-50 in the summer for over 25 years. Change every 4-5K. Some would say this is not optimum, but guess what? No sludge, no wear problems.

Last oil change I used Castrol Syntec 10-40. May stay with the synthetic from now on. It should have better start up qualities and last a little longer and wear protection should be somewhat better. Technology changes...

I had a really bad experience with Mobil 1 in it's first formulation. But that was in my motorcycle which is a quite different beast (wet clutch). Still there were some car issues too, but they were addressed long ago.

Careful about filters. Some don't have the flow back check valve. I believe that Wix does. Obviously Audi filter do too. Don't know who makes them, maybe Mann?

 

Audi recommends service every 10k miles... They recommended an oil change every 5k.

the 10k interval service is covered under warranty aslong as you purchased a maintenance package.

the 5k oil change is on the owner to perform on their own, whether they bring it somewhere or do it themselves

 

Mobil 1 is certainly good, but not the best. We've been discussing for some time on the Porsche boards. 0W40 is good too, but if you live in a warm climate, try something thicker.

 

Mobil 1 5W-40 Turbo Diesel Truck oil.. Ticking is gone, sludge is about gone, MPG is up +2

edit: oh, and believe it or not, I smoked out the back when floored when I first bought this thing and used a quart every tank... ALL GONE.. no smoke, and only 1/4 quart in the last 5 or so tanks... So that crap about synthetic 'causes' leaks and oil burn, is.. crap.