2004 X5 maintenance
 

I have a 2004 with 105k. I completed all services with the bmw dealer. What type of maintenance do i need to prevent high service costs? Do i need to replace the water pump, or timing chain? Other than change the oil, any other suggestions?

Which engine?

There isn't usually need to change the timing chain until very high milage. Chain tensioner might start making noise at some point, so that can be changed separately if noise comes too loud.

At your mileage, spark plugs and the O² sensors are due for replacement regardless of drivetrain. If they haven't been done, change them. I'm not sure about the O² sensor, but spark plugs are an easy DIY.

Flush the coolant, transfer case fluid, and ATF if not already done so. Have the serpentine belt checked for cracks.