During the last visit to my BMW dealership, the technician told me the recommended coolant flush was every three years. Under the three year maintenance agreement, I will have this done free of charge, as the three years is based on the build date, not the date the car was purchased. If you have a newer car, you may want to check the build date on the door tag, and make sure you get the car in after that but before the in-service date if you want the service for free. Last week I went to have the Transmission Fluid changed on my 40k car and was told that it is a sealed system from the factory and is good for the life of the transmission .... riiight! Must be, becaue I cannot find any filler tube, etc. Then I asked about flushing the coolant and was given a similar story. My question is, if I decide to flush the coolant on my own, can I use the long life antifreeze (Prestone, etc.) or do I have to use the stealer recomended $40 gallon stuff? Also, why is it available, if it is good for the life of the car?