Technical Articles
Brake Literature
What is DOT specification?
DOT is the abbreviation for the ‘Department of Transportation’, which is an American government transportation department. The DOT set standards such as FMVSS (Federal Motor Vehicle Safety Standard) very similar to the JIS in Japan or DIN in Germany. The following table shows the DOT brake fluid specifications:
| Specification | Main ingredient | Dry Boiling Temp | Wet Boiling Temp | Viscosity (100℃) | Viscosity (－40℃) | Ph Value |
|---|---|---|---|---|---|---|
| DOT 3 | Glycol | over 205℃ | over 140℃ | over 1.5cst | under 1500cst | 7.0-11.5 |
| DOT 4 | Glycol | over 230℃ | over 155℃ | over 1.5cst | under 1800cst | 7.0-11.5 |
| DOT 5.1 | Glycol | over 260℃ | over 180℃ | over 1.5cst | under 900cst | 7.0-11.5 |
| DOT 5 | Silicon | over 260℃ | over 180℃ | over 1.5cst | under 900cst | 7.0-11.5 |
□ Dry Boiling Temp. : Boiling point when the fluid is brand new, no moisture absorption.
□ Wet Boiling Temp. : Boiling point with fluid that has 3.7% water by volume. After 1-2 years of fluid use.
□ Viscosity : a measure to represent the brake fluid flow property. Higher the value, the more difficult for the fluid to flow. If the value is high when the air temperature is low, the fluid can have a negative effect on ABS performance.
□ pH value : value to show acidity / basicity of a solution. If the pH value is lower than 7.0 (strong acidity), the fluid can accelerate corrosion of other brake components