quote:Originally posted by Cowboy from Hell:
The absence of water absorbtion in DOT 5 fluid is a blessing and a curse. Any water that gets into a system containing DOT 5 will form steam pockets when the temperatures rise, and steam is very compressible.
Racers sought DOT 5 because of it's high boiling point but soon found that since it cannot absorb water that it took very very little water to cause total brake failure. Racers who cautiously use DOT5 today change their fluid before every event and some events even require it. A drop or two of water in DOT5 will migrate to the lowest point which is your caliper and ruin your hole day. Non-silicoln brake fluid can absorb a couple oz of water before it becomes a problem so suddenly the advantage of absorbing water appears.
DOT 5 has become the choice for car collectors who rarely use their car and never get their brakes hot enough to boil water.