Q: What kind of transmission fluid do I need for a BMW 525i 2007 ?

Hi There, The transmission in your BMW 525i is what is called a "sealed unit" which means that the transmission should not ever need to be flushed or have the fluid changed. This means that in the event you may need to add fluid to the transmission, it may be likely that you have a leak somewhere which may be a sign of a larger problem. For purposes of topping off the fluid, you should refer to your owner’s manual or the local BMW dealership as these vehicles require a very specific fluid. In your case, your transmission will require BMW ATF II fluid.