As Adam says however we did have some discussion about this before as the seals on the Nissin stuff share the same part numbers between the DOT 4 and 5 bikes.
All my Buells use DOT 4 or 5.1 cos rather than let water collect in pockets, it absorbs it and hence when you bleed your brakes you get rid of all the stuff you don't want.
There is a lot of guff spoken about hydraulics, a Ducati expert told me the other day that no Brembo seals are compatible with DOT 5 as they are natural rubber yet the first S1s and the S2s had Brembo at the rear and used DOT 5
