I just purchased a 2002 A6 Quattro and don't have an owners manual. I want to get teh oil changed and don't know what I can use or what is reccomended

 

(Re: N. America)Any API certified 5W30 should be adequate for your `02 Audi...but a VW/Audi approved (502.00/505.00) 5W40 synthetic will provide high-stress protection for at least 5k miles. FWIW, Audi-approved synthetic motor oil didn't become mandatory until the `05 M.Y..

UberTeile

 

these two are best ;
Castrol Syntec 5W-30 (this gives you better MPG than M-1 below, & Audi dealers use it)
Mobil 1 European formula 0W-40

 

I just had my 55k Service (06 A6, 4.2) and asked if they stocked Royal Purple or just Mobil1 and the Tech* replied "We have Mobil1 but your car calls for Castrol Syntec." He sounded like he knew what he was talking about and this echos what bigdadi said so I would be inclined to go with that.

*I had the service done at a euro autohaus and not an Audi dealership.