Brake Fluid DOT Ratings
DOT ratings classify brake fluids by boiling point and chemistry, mainly DOT 3, DOT 4, DOT 5 and DOT 5.1.
What is Brake Fluid DOT Ratings?
DOT 3, 4 and 5.1 are glycol-based and can generally be mixed. DOT 5 is silicone-based and must not be mixed with the others. Higher numbers mostly mean higher minimum boiling points. A brake fluid tester measures water content and shows when a change is due.
How it works
Standards set minimum dry and wet boiling points for each class.
Why it matters for your car
Glycol fluids absorb water over time; change them as scheduled. Use the type stated on the reservoir cap.
Other terms
- Auto Hold (Brake Hold)
- Blocking Fee (Idle Fee)
- C-Pillar
- Car Wax And Paint Sealant
- Centre Console
- CO₂ Emissions (G/km)
- Electronic Parking Brake
- EV Mode (Electric-only Mode)
- Idle Speed Control
- Impact Wrench (Impact Gun)
- Insulation Monitoring (Isolation Fault)
- Matching Numbers
- Oil Filter
- Oil Pressure Warning Light
- Pedestrian And Cyclist Detection
- Pending Code
- Steering Play (Free Play)
- Trolley Jack (Floor Jack)
- Variable Geometry Turbocharger (VGT)
- Variable Valve Timing (VVT)