Quote Originally Posted by KenWilkinson View Post
Why is DOT 5 Silicone not recommended?
It can be and has been discussed ad nauseum. Here's a cut & paste of a response I made to the same question a few years ago:

...trust me on this---DO NOT USE DOT5. In a nutshell it is a silicone fluid and retains millions of tiny air bubbles making it compressible meaning you will never get a firm pedal. Additionally it is non-hygroscopic (does not mix with water) so any moisture will stay separated and since H2O is heavier than the silicone it will settle in the low points; i.e. calipers. Get the brakes hot, the water boils and you have no brakes! Stick with glycol based DOT3, 4 or 5.1 fluid.

Jeff