It's crazy to wait that long

BMW also tells you that their Trans fluids are "lifetime" fills, and that the fuel filter never needs changing. What "lifetime" means to a BMW dealer is Lifetime of the warranty period. Remember that. They care about getting you through your Warranty period with a minimum of issues. They are NOT interested in ensuring the long life of your car.

Every time a BMW service "adviser" tells you that something on your car is a "lifetime" fill or component, You can tell them as soon as BMW gives you a lifetime warranty on that part, you'll listen to their maintenance recommendations. Otherwise, you should use the maintenance schedule recommended by Mike Miller of Bimmer magazine, which is basically the maintenance schedule BMW had before they started paying for maintenance, and all the intervals magically doubled, or even went away.

I'd change your oil at least every 7500 miles, even with synthetic. At least BMW will then pay for every OTHER oil change.