My A6 2.8 is using a quart of oil every two weeks. Under normal city driving conditions. No apparent leaks, no drip on the driveway. No blue smoke or burning oil smell from the exaust. My first thought is valve guide/stem seals. I have never had the valve covers off of this engine. It currently has 141,000 miles on it. We bought it last spring. It's a great car, want to get the oil consumption probelm solved. Anyone have a simular problem? What was the fix?