Spent some coin at the local BMW dealership on some fluids for the M3. I got 9 bottles of engine oil, 3 bottles of trans oil and 3 bottles of diff oil. That was a bit pricey coming from Z-land, but to be expected. I got the engine oil changed no problem.
Dave, since you've crossed over to the German dark side let me introduce you to your new go to site for maintenance items: https://www.ecstuning.com/. Its one of the best websites I've seen for organization, staggering amount of fluids and OEM vs OE parts options, tools, high quality pics of damn near every part and prices that can't be beat (I've tried many other parts sites usually the best the others can do is match prices on parts but its spotty at best). Best of all its been years since I've stepped foot in a VW/BMW/Audi dealer for parts/fluids and my wallet thanks me every time. ECS used to have free shipping for $200 or more and now its down to $50 so basically free shipping, even if its like 100lbs of fluids and parts in multiple boxes. They recently joined forces with Turner so their BMW force is even stronger. They do have some nice in house designed mild aftermarket stuff, but I've mostly used their deviations from OEM for design improvements on failure prone parts for simple things like steel plugs after your aluminum plug failed. For hard core racing/track mods your best bet is still Bimmerworld, Turner, Vorshlag.
Also for the new plug you installed you may want to put an o-ring under it, if you haven't already, since the OE plug had an integral seal on it.