0.47 L is the amount of oil, It says to use BMW telescopic fork oil I guess as it does not do any damping a lightweight fork oil will do just help the fork tubes slide.
Hi Delpel,
When I replaced fork seals I just bought the genuine B*W oil - it's not too expensive and as long as you've got a dealer in you part of the world it's maybe easiest. It comes in a 1 litre bottle so at 0.47L per leg it's just enough, it says on the bottle thats it's 10w viscosity telescopic fork oil!