It should be API SP which was designed to reduce the chances of low speed pre-ignition - LSPI which is an issue with turbo-charged engines. Its should also have a medium ash content due to the CAT. Fully synthetic is also a requirement due to the high temps in the turbo. BMW also recommend an LL spec oil. Put all this together and you end up with Castol Edge ( the API SP version which is a later spec) or Motul 8100 eco-clean 0w-30, both of these are used by at least one dealer I spoke to. I believe the factory use a Miller oil but I dont know what the precise spec is. Frequent oil changes are probably more important that the spec as BMW have a habit of leaving the oil in too long! Good luck!
