FWIW I replaced the battery in my 2001 X5 with a 3rd party battery at roughly 50k miles. About a year later when I took it in for a repair to an electrical problem ( the left fog light was not working) the BMW Dealer required me to replace the 3rd party battery with a BMW approved battery before they would repair the fog light under extended warranty. I argued that this was silly but lost anyway

Funf Dreisig

Edit: fixed date. Apparently the right hand knows not what the left hand is doing