I ran a search and found some seem to be using dot 3 and some dot 4 brake fluid. Is this like starting an oil thread over on the Mercedes Diesel forum where it is a huge can of worms?
I do know from my experience in road cars that some brake fluids will eat away some brake seals and you need to be careful. My experience is that the european rubber parts may be a little more sensitive to brake fluid composition than American seals.