Wonder what the Audi dealer she got it at uses if she brought it to them for OCI. I know the bulk oil at mine uses the VW/Audi labeled Mobil 1ESP X2 0W-20, which is an excellent oil for low visc. speced applications. It's VW508/509 and ACEA C5, but don't know if the M1 is BMW rated at all. But if they would use that and a Mann/Mahle/Hengst filter, I can't see really going wrong there.
Even after warranty, don't know if there would be a real NEED for anything higher unless specific use dictates it, ie; track use, etc.