***.. people..
Dot 4 is std fitment grade of fluid, HOWEVER, there is a hell of a range of products which all fall into Dot 4 class, based on their hygroscopic properties.. (moisture absorbtion)
Dot 5.1 is the next level of less hygroscopic fluid, BUT, it does not make it a better high temp fluid..
Most racing fluids, like the Motul RBF600/660 I sell and use personally, are Dot4 fluids but have extremely high dry boil temps, which is why they are good fluids..
Dot5 is a silicon brake fluid and NOT what you want to be using in your system at all.... it is not compatible with other fluids.
Fluids for full bleed is between 2-3 bottles worth of Motul, which is 500ml bottles, so 1-1.5ltrs
Dot4 is supposed to be changed every 2 years in road cars, as the fluids take up moisture over the lifetime, and this reduces the boil point over time.
regards
bill