Engine oil OEM BMW or Pentosin

Based on extensive testing, BMW has approved only certain engine oils. Use only approved "BMW High Performance Synthetic Oil." If you are unable to obtain "BMW High Performance Synthetic Oil," you can add small amounts of synthetic oil in between oil changes.

pentosin/pentosynth 5W40 here, changed it 1K miles ago (second run on this oil), great stuff ecstuning.com sell it for ~28 bucks for 5 liter. I like it much, much more over the castrol from dealership (used that too and after 2K miles changed back to pentsynth). I'm very happy with it.