Does anyone know if there is any overall benefit or engine life extension associated with doing an oil system flush instead of just doing an oil and filter change as required (drain and fill)? I use 5W-30 synthetic and change it out about every 8-9K miles. I still hope to get alot more life out of my M62 engine.
Generally speaking there is no benefit to an engine flush unless the engine has a build-up of sludge, usually associated with high mileage engines that have not had proper maintenance. With your regular oil changes it's highly unlikely that you would see any benefit with an engine flush, in my experience. I would use the oil specified by BMW for your engine and keep changing it at regular intervals.