Totally out of convenience, I dumped the GC out of my mother-in-laws A6 and went for the really cheap service at Wal*Mart. For $30 they give you 5 quarts of your choice of synthetic and a Fram/SuperTech filter change. Fortunately, they don't list a filter for this car so I just bring my own Bosch Premium. That is basicly $25 worth of oil, changed for another $5! I really went for tire rotation at a reasonable $1.50 each and the oil service was tempting enough to do it. 5 quarts of Mobil 1 0w-40 is included and I topped off myself with some M1 10w-30 I had laying around. A good deal, they even credited me $2 for byo filter. The Mobil seemed really thick compared to the Syntec, less power but very quiet and smooth. I was interested in keeping ester oil in there to help with seals at 105,000 miles. We are set for 6 months, I will probaly do the June change myself. I could have run the GC out until May-June, but I don't need to push to 10,000 miles OCI and have worse consumption when Wal*Mart is so cheap.