Brake Doctor – What types of brake fluid are available?
There are basically two types of fluid: glycol-based and silicone-based. You can use one or the other, but NEVER mix the two fluids. If you want to use a different fluid than the one in your system (glycol to silicone / silicone to glycol) then you will need to flush the system before changing. Brake fluid is available in different specifications to meet American Department Of Transport (DOT) requirements. These DOT regulations are occasionally updated but basically the higher the DOT rating the higher quality, higher boiling point and more expensive the fluid. DOT3 is the basic brake fluid. DOT4 is a higher standard and both of these fluids absorb water – they are hydroscopic, but DOT4 fluid contains additives which prevent water affecting the fluids performance to the same degree. DOT5 was originally formulated for silicone based brake fluid although there is now a new DOT5.1 standard for glycol based fluid which has some of the desirable properties of silicone fluids. Both types – g
