Originally Posted by powers1

Eddie,as you probably read here,the oil in the K&N filter can damaged your MAF (your air temperature sensor ).If you are fitting a K&N at least ensure that you remove the majority of the oil by tapping the filter onto a cloth.
If you are going to remove your air-filter yourself ,you first have to remove the plastic air scoops at the front,remove the valve cover,remove the alen screws on the air-filter cover.Note that you have 2 screws that are very difficult to access !!These are further back of the engine,one on the left and the other towards the back of your air-filter cover!You need an L-shaped alen key and LOTS OF PATIENCE!!!!Perhaps you should let your dealer do it?

I dont know who supplies BMW their batteries but you dont have to get an oem battery!Your battery is 12V 90AH 720A,so any good brand with these specs will fit your X5.