This. Toptier gas for their detergents. BMW/techron for their fuel injection cleaner. I also highly recommend BG 44KTry these threads:
BMW sells Chevron Techron in their own bottle. Using it every 6 months would be good enough.
If you use a top tier gasoline it already has more cleaning agents included.
Chevron/Texaco gasoline already has a small dose of Techron, if you have Texaco or Chevron stations in your area.