Depend on how the car being driven, BMW is designed to perform as almost as race car, It will automatic unclog the passage if we drive aggressive as BMW intended to perform. However, we've like to take care our car and drive at moderate speed, long idle, and stop and go; it will be clogged around 70,000 miles.
To extend the mileage of between cloggings, BMW cars need to drive at 5,000 RPM (highway at 3rd gear up to 60 mph) for 10 minutes once a week; more than 10 minutes probably will over heat the transmission and won't be recommended. Or the other way around is to follow the Youtube procedure above twice a year or 7,000 miles whichever comes first.
Last edited by Ricardo567; 01-26-2013 at 04:05 PM.