There are three different kinds of brake fluid: DOT 3, DOT 4, and DOT 5.
DOT 3 an DOT 4 are glycol-based fluids which means they can absorb water. DOT 3 and DOT 4 will congeal at -40F, but if they are contaminated with water, that temperature does not need to dip down that low.
DOT 5 is a silicone based brake fluid which does not absorb water, and this makes a big difference. Its freezing point is still about -40F, but since it does not absorb moisture from the air, its freezing point does not fluctuate.
You may be wondering why all cars don’t use DOT 5 then? It would mean fewer fluid changes and fewer brake failures.
There is one problem with DOT 5. It doesn’t work well with anti-lock brake systems, and anti-lock brakes are very effective in helping you stay in control of your car when it begins to skid.
so, only use the DOT type the car specifies, in our cars, is DOT4
DOT 3 an DOT 4 are glycol-based fluids which means they can absorb water. DOT 3 and DOT 4 will congeal at -40F, but if they are contaminated with water, that temperature does not need to dip down that low.
DOT 5 is a silicone based brake fluid which does not absorb water, and this makes a big difference. Its freezing point is still about -40F, but since it does not absorb moisture from the air, its freezing point does not fluctuate.
You may be wondering why all cars don’t use DOT 5 then? It would mean fewer fluid changes and fewer brake failures.
There is one problem with DOT 5. It doesn’t work well with anti-lock brake systems, and anti-lock brakes are very effective in helping you stay in control of your car when it begins to skid.
so, only use the DOT type the car specifies, in our cars, is DOT4
