[Jeff Higgins]

I've been using dual rated DOT 3 and 4 for decades. I honestly have no idea why the industry still supports separate 3 and 4 ratings. You found the right stuff, Denis. Use it and never look back.

I have had vehicles that specify DOT 5. Yes, it is silicone, not glycol based. Can't mix it with 3 or 4. The whole idea was that it is not hydroscopic, so it will not attract water. My '76 Sportster specifies it, as did my 2000 Road King. I made the mistake years ago of putting the 3 and 4 into the Sportster to top it off and created one hell of a mess. It just gelled right up into little blobs, clogging the master and brake cylinders along with the brake line. It was a real job cleaning it all out.

Years later, after having replaced the entire hydraulic system on that front brake, I thought I could take advantage of everything new and just switch to 3 and 4. Hah! - Higgins, you idiot... turned out the materials used in the cylinders and line were not compatible with 3 and 4. Another hell of a mess to clean up, and now rubber parts to replace. So not only do the fluids not mix, the materials used in the brake cylinders, master and slave, along with the brake line, may not be cross compatible. Dot 5 is evil. Never should have been invented.