What engine oil to use in servicing

[Pyrrho]

I just buy the BMW recommended oil from the local dealer, and will continue to do so.

BMW doesn't make oil, they just partner with a manufacturer to put their label on it and push it through their dealer network. Any SAE 5W-40 APO SL / JASO MA2 motorcycle oil will work just fine, won't void your warranty, etc.

Look at Motul, Castrol Power1, Shell Rotella, Havoline, etc. Google "SAE 5W-40, API SL / JASO MA2". Oil isn't rocket science so don't fall for retail science and buy whatever the manufacturer says, especially when the manufacturer is also selling you the overpriced thing their paid employee is telling you to buy.