2004 E64 645 auto box
My 2004 (54) E64 645 Ci mileage 72,000
Took it to my Independant in Bristol who changed the plastic sump, filter, oil, as the gear change had been notchy on occasions.
When they took it down, it had half the required oil, and it was black! All put back together, fresh oil etc. Wow what a difference! Smooth, quiet with no snatched gear changes.
BMW will tell you it's 'For Life'. My independant tells me if I hadn't had it done when I did the car would have been uneconomical to repair!
Total cost (UK) £140 for new sump, gasket and oem oil. £150 labour to remove replace and refit. £290 in total. New gearbox £5500 recon £3500
Well worth it I reckon. Hopefully good for another 10 years!