Another downside to DOT 5 is that if you ever get a significant amount of moisture in the system you can get severe brake fade if that part of the system gets above 212 deg F. That's because the moisture is not soluble in DOT 5 so that little drop of moisture will boil at 212 deg F. For the glycol based fluids the moisture is soluble and the boiling point will be somewhere between 212 and the boiling point of the dry fluid. That's another reason DOT 5 fluids need to be changed regularly.
