To find out which type your M5 takes, look on the reservoir tank, under the white translucent plastic cover. Never mix with another type, it could rot your system's seals. You should see a tag or sticker there which tells you what to use. In my case, almost 100% of the Pentosin had leaked out. It took ~1.5 l. to bring it up to the mid-point between the correct level markers molded into the tank.

I also replaced both accumulator$ and both hoses. Total cost from MLD with my discount was $493.00. The accumulators are NOT the same ones as used for the brakes!