Brake Fluid Buying Guide
Paskutinį kartą atnaujinta: 2026 m. balandžio 24 d.
Brake fluid is a hydraulic medium that transfers pedal pressure to the brake calipers and wheel cylinders. It is hygroscopic, meaning it absorbs moisture from the atmosphere over time. Contaminated fluid lowers the boiling point, risking brake fade under hard braking. Regular replacement is essential for safe braking performance.
When to change brake fluid
Most manufacturers recommend a brake fluid change every two years regardless of mileage. Moisture absorption is time-dependent, not distance-dependent.
- Spongy or soft brake pedal feel indicates air or moisture in the system
- Brake fluid colour has turned dark brown or black (fresh fluid is clear to light amber)
- MOT advisory for high moisture content measured with a brake fluid tester
- After any brake hydraulic component replacement (caliper, hose, master cylinder)
Choosing the correct brake fluid
Brake fluid is classified by DOT ratings. Using the wrong specification can cause seal damage and braking failure.
- DOT 3: older vehicles with conventional braking systems
- DOT 4: most modern passenger cars, higher boiling point than DOT 3
- DOT 5.1: synthetic, highest boiling point for glycol-based fluids, compatible with DOT 3/4
- DOT 5: silicone-based, NOT compatible with DOT 3/4 systems. Rare in standard vehicles
- Always check your vehicle handbook for the correct specification
Kategorijos puslapis
- Peržiūrėti tinkamas dalis
DOT 3, DOT 4, DOT 5.1 explained — dry and wet boiling points, hygroscopic ageing, and when to flush your brake fluid.
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Dažnai užduodami klausimai
How often should brake fluid be changed?
Every two years regardless of mileage. Brake fluid absorbs moisture from the atmosphere, which lowers its boiling point and can cause brake fade under hard braking.
Can I mix DOT 3 and DOT 4 brake fluid?
Yes, DOT 3 and DOT 4 are both glycol-based and can be mixed in an emergency, but the system will perform to the lower specification. A full fluid change to the correct DOT rating is recommended.
What is brake fade?
Brake fade occurs when overheated or moisture-contaminated fluid boils in the calipers, creating gas bubbles that compress instead of transmitting pressure. The pedal goes soft and braking force is drastically reduced.
Is DOT 5 brake fluid better?
DOT 5 is silicone-based and does not absorb moisture, but it is NOT compatible with standard DOT 3/4 systems. It is used in specialist and military vehicles. Most cars require DOT 4 or DOT 5.1.
How much does brake fluid replacement cost?
The price of brake fluid depends on the specification your vehicle requires. Enter your registration above to see parts confirmed to fit, then compare prices from the brands we stock on this page. Free UK delivery on orders over £99.
Susiję gidai
ABS ir ESC įspėjamosios lemputės — rato greičio jutiklio diagnostika, impulsinio žiedo patikra ir keitimo vadovas.
Brake Master Cylinder Buying GuideSpongy or sinking brake pedal? How to diagnose a failing brake master cylinder, bleed the system, and choose the right replacement.
Brake Shoe Set Buying GuideRear drum brake shoes — lining materials, wear limits, self-adjusting mechanisms, and how to replace brake shoes safely.
Rankinio stabdžio troso pirkimo vadovasRankinis stabdis nelaiko įkalnėje? Troso ištempimas, užstrigę mechanizmai ir stovėjimo stabdžio trosų keitimo patarimai.
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