Hi, I have just done mine with no ill effects at all. They warned me that they had to use a suppliment which I think is a synthetic additive to stop shudder but no big deal at all. BMW in their wisdom did not provide the usual couplings for flushing so they will have to do filter etc then fill and drain from the GB openings. They did mine twice(drain, fill, run & flush) and now it's good. There is no dip stick as the box was "sealed for life". Sadly, life was 6000 miles.