I have to bleed my brakes and was goint to changeout the fluid while I was at it. The master cylinder cover says use DOT 4 only (do you realy have to follow that?). I looking to get a few opions on what to use. I have not visited a bike shop to look at what they had on the shelf, but saw some Valveline Synthetic autoparts store that said it was DOT 3 or 4. All the rest of the fluids were DOT 3. Is the valveline any good? Does any one know the difference between the DOT levels of the fluid?