DOT 5

DOT 5 is one of several North American designations of automotive hydraulic brake fluid, denoting a particular mixture of chemicals imparting specified ranges of boiling point.

DOT 5 is a silicone-based brake fluid (contains at least 70% by weight of a diorgano polysiloxane^[1]).

Unlike polyethylene glycol based fluids, it is hydrophobic. An advantage over other forms of brake fluid is that silicone has a more stable viscosity index over a wider temperature range. Another property is that it does not damage paint.^{[citation needed]}

Using DOT 5 in a DOT 3 or DOT 4 system without proper flushing will cause damage to the seals and cause brake failure.^{[citation needed]} DOT 5 brake fluid is not compatible with anti-lock brake systems. DOT 5 brake fluid absorbs a small amount of air requiring care when bleeding the system of air. ^{[citation needed]}

Boiling points

Minimal boiling points for these specifications are as follows (wet boiling point defined as 3.7% water by volume):

References

1. ↑ Standard No. 116; Motor vehicle brake fluids Code of Federal Regulations, Title 49 - Transportation, Chapter V - Part 571 - Federal Motor Vehicle Safety Standards (49CFR571), Subpart B, Sec. 571.116 Standard No. 116; Motor vehicle brake fluids
2. ↑ FMVSS 116

dot 5