Yes, especially the wet boiling point. There are DOT 5.1 and 6.1 available with wet boiling points up to 412 degrees F. Since all brake fluids (except DOT 5.0) are hygroscopic, the wet boiling point sound be as a reference. Jim Davis 04:41 PM 5/29/2004, you wrote: >Is the biggest/only difference between Dot 3 and Dot 4 brake >fluid the boiling point? > >Chuck Armer > >Corvair Atlanta,