Thanks for this info, it is very helpful. I just bought a 2005 S4 with 127K miles. No rattle, and runs really smooth. You suggest using high quality oil, and I have read other places that using a heavier weight oil will also help. I can see that a heavier oil would have advantages because it would be less likely to bleed oil pressure as you mentioned in one of the early posts. But I can see that a lower weight oil would have advantages of getting through the timing components faster once the engine is started. For preventative care would you recommend a heavier weight oil, a lighter weight oil, or just to stick with the spec oil?