Brake fluid: level and bleed

Brake fluid transmits pedal force to the calipers and cylinders. A correct level and fluid in good condition are essential for safety.

Level and marks

The reservoir is usually visible under the bonnet, on the master cylinder. Min and max marks indicate the normal range. The level should stay between these two marks. If the level drops regularly, there may be a leak in the circuit: have it checked without delay. A slow drop can be linked to pad wear (pistons extend, level drops slightly): monitor it.

When to check

Check the level at each oil change or recommended service, and before a long trip. If the brake warning light comes on on the dashboard, stop safely and check the level and condition of the circuit. Never drive on if the level is below minimum or if a leak is visible.

Bleeding the circuit

Bleeding consists of renewing the fluid and removing air from the circuit. It is recommended every 2 years or according to the manufacturer’s recommendations (often 40,000–60,000 km). Hygroscopic fluid absorbs moisture; over time its boiling point drops and braking can become less effective. Regular bleeding limits this risk.

Fluid type

Use only the type specified by the manufacturer (DOT 3, DOT 4, DOT 5.1, etc.). Do not mix different standards. Brake fluid is corrosive: avoid contact with paint and eyes.

My Auto Check-up helps you track your vehicle’s symptoms to anticipate maintenance and safety.