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Brake fluid Audi A4 B9 (2015–2023) — DOT4 specification

Brake fluid for Audi A4 B9 (2015–2023) — required specification, boiling points, system volume, and approved brands.

Specifiche tecniche

ParameterValue
Marca / ModelloAudi A4 B9
Anni di produzione2015–2023
Specifica del liquidoDOT4
Punto di ebollizione secco230°C
Punto di ebollizione umido155°C
Volume del sistema600 ml
Intervallo di sostituzione30 000 km / anni

Marchi approvati

Audi/VW DOT4, ATE SL.6, Liqui Moly DOT4

Why Brake Fluid Must Be Changed Regularly

Brake fluid is hygroscopic — it absorbs moisture from the air over time. As moisture content increases, the boiling point drops significantly. When the fluid boils under heavy braking, vapour bubbles form and the pedal goes to the floor (vapour lock). Audi requires DOT4 with a dry boiling point of at least 230°C.

How to Check Brake Fluid Condition

  1. Test strips — dip a strip in the reservoir; colour indicates moisture content
  2. Electronic tester — measures boiling point directly (most accurate)
  3. Visual inspection — dark/brown fluid indicates it must be replaced (fresh fluid is amber/clear)

Domande frequenti

What brake fluid does Audi A4 B9 use?

DOT4 specification. Punto di ebollizione secco: 230°C. Volume del sistema: 600 ml. Marchi approvati: Audi/VW DOT4, ATE SL.6, Liqui Moly DOT4.

How often should I change brake fluid in Audi A4 B9?

Every 30 000 km or every anni — whichever comes first. This is a safety-critical service.

Can I mix different DOT grades?

You can mix DOT 3 and DOT 4 in an emergency, but never mix DOT 5 (silicone-based) with DOT 3/4 (glycol-based). Always use the correct specification: DOT4.