I NEVER use silicone DOT 5 fluids in motorcycle brake
systems. It aerates badly quite easily, and although it holds against
temperature well, the other issues with it,, as it needs to be gravity fed so as
to NOT hold air bubbles, not pressure bled, just isn't worth the effort and
On John Cornwell's 250's, with nice Brembo, Lockheed, Japanese and IRS brake components, six piston stuff, we'd run the bike for a test session or heat race with DOT 5 fluid, and have to reverse bleed it after every session on the race track, in futile attempts to get all the air bubbles out of it. Even the recommended gravity bleeding didn't keep the air bubbles out of the DOT 5.
Switching to DOT 4 fluids cured the brake aeration issues and we got nice brakes after that, no fade, no bubbles, no overheating (which was not an issue with the DOT 5), just great stopping power.
As far as I have experienced, DOT 5 fluid may well be just peachy in a Corvette, but it loses all the way around in a motorcycle brake system. Just my hands on experiences.