In an ideal world, we'd replace everything one time and be done with it. but I am my own service manager so I only replace what needs replacement. I do have my eye on my cars
so yesterday I replaced my X's expansion tank. with it I replaced it with the level sensor. went with genuine BMW. My old tank is dated 06 so the tank lasts about 5years.
pics of the new tank
pics of the new level sensor (old one on the left, new one on the right)