Brake Fluid

[Bob In Ct]

While it has very good high temperature qualities DOT 5 is not very tolerant of water (which is fine if you're changing it after every race). If not, the water which finds its way into the system may not be absorbed by the fluid and is then able to rust components. DOT3 is much better at absorbing water and therefore makes a much better fluid for daily drivers.

Bob

[JST4FUN]

I just changed mine this week using Valvoline Synthetic DOT 3&4. My research revealed DOT 3, 4 & 5.1 were my choices with each having both a higher dry and wet boiling point as the number increased. Also, DOT 5.0 is silicon based and not compatible with the other 3. In fact, my SPF manual recommended against using 5.0. I couldn't readily find 5.1 locally, so I used the highest boiling point product I could find here without ordering it.