Deciphering the Chemistry: A Guide To Brake Fluid Composition

Your vehicle’s braking system is a critical component of its safety, and brake fluid plays a pivotal role in ensuring smooth and reliable braking performance. But what exactly is brake fluid, and what goes into its composition? In this guide, we will delve into the chemistry behind brake fluid, exploring its composition and understanding why it is vital for your vehicle’s safety. Find here the best brake fluid manufacturer for your business needs.

Introduction to brake fluid:

Brake fluid is a hydraulic fluid that transfers force from the brake pedal to the brake components at each wheel. It is a non-compressible substance that must withstand high temperatures and extreme pressure while remaining stable over time. Two primary types of brake fluid are used in vehicles today: glycol-based and silicone-based.

Glycol-based brake fluid:


Glycol-based brake fluid, the most commonly used type, is typically composed of a mix of glycols, water, and various additives. The glycols used are usually ethylene glycol or diethylene glycol.

Hygroscopic nature:

One of the critical characteristics of glycol-based brake fluid is its hygroscopic nature, meaning it readily absorbs moisture from the atmosphere. This moisture can lead to a decrease in boiling point and, in severe cases, result in brake system corrosion.

DOT ratings:

Glycol-based brake fluids are categorized into DOT3, DOT4, and DOT5.1, with each having different specifications and performance characteristics. The DOT rating indicates the fluid’s boiling point and its ability to resist moisture absorption.

Silicone-based brake fluid:


Silicone-based brake fluid, unlike glycol-based variants, does not contain glycols or water. It consists primarily of silicone polymers and various additives.

Hydrophobic nature:

Silicone brake fluid is hydrophobic, meaning it repels water rather than absorbing it. This characteristic provides it with a significantly higher boiling point and resistance to moisture-related issues.


Silicone-based brake fluid is not compatible with glycol-based fluids. Mixing them can lead to brake system damage, making it crucial to ensure the correct type is used when topping up or flushing the brake system.

Additives and inhibitors:

Both glycol and silicone-based brake fluids include additives and inhibitors to enhance their performance and longevity. These additives are designed to prevent corrosion, reduce foaming, and maintain fluid stability under extreme conditions.

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