Brake Fluid – When did you flush yours last?

The most over looked fluid in a vehicle is the brake fluid. It’s tasked with stopping a moving vehicle and takes a lot of abuse.

One of the main characteristics of glycol based brake fluid is that it is hygroscopic, meaning it absorbs moisture. As this happens the boiling point goes down causing a decrease in the effectiveness of the fluid which translates into greater stopping distance and a softer pedal. Under extreme conditions, brake fluid with high moisture content can boil and vaporize resulting in a loss of brakes. This is the main reason why it is recommended to replace the brake fluid in any vehicle every 2 years by flushing the system.

Another problem with having water in your brake lines deals with corrosion.  After many years of aging, your brake system can literally rot from the inside out.  This is very detrimental to the insides of your Master cylinder, brake calipers, brake lines, ABS module and any other steel/alloy components that are in constant contact with spoiled brake fluid.  If you have ever bought an older car and had to redo the entire braking system, it was most likely due to old brake fluid.

Even in the bottle, brake fluid has a limited shelf life. When adding fluid to the system, always use fresh fluid from a sealed container, because once opened the fluid starts to absorb moisture and the clock starts ticking.

Brake Fluid Types

EBC Dot4+ Racing Brake Fluid

There are several types of brake fluid on the market today and we’ll help you choose which type is best for your application. DOT 3 and DOT 4 are used on passenger vehicles. Most European manufacturers use DOT 4.

DOT 3: Glycol-based fluid with a minimum dry boiling point of 401 degrees Fahrenheit. Compatible with DOT 4.

DOT 4: Glycol-based fluid with the addition of Borate ester.  It generally has a minimum boiling point of 446 degrees Fahrenheit. Compatible with Dot 3.

Dot 4+: This is mostly the same as a standard DOT4 fluid, with a few changes to increase the boiling point.  Our EBC Dot4+ racing fluid has a dry boiling point of nearly 600 degrees Fahrenheit!

DOT 5: This is a silicon-based fluid. This fluid is NOT recommended for use on the street or track. Never use silicone fluid in a vehicle equipped with ABS because the modulation of the ABS pump will cause the fluid to foam. The only advantage to using this fluid is in a show car that will not be driven because the fluid will not absorb moisture and it will not damage painted surfaces.

DOT 5.1: This is the non-silicone version of DOT 5. It is a glycol/Borate-based fluid which meets same the specs as DOT 5 fluids and it has a minimum dry boiling point of 500 degrees Fahrenheit. DOT 5.1 is compatible with DOT 3 and DOT 4 and can be mixed.

You may also find the term ‘Low-Viscosity‘ used in the description.  Low-Viscosity brake fluids are becoming increasingly popular among automobile manufacturers due to the ability of the ABS system to micromanage the fluid flow.  The lower the viscosity, the quicker the reaction time can be through the small passageways of the ABS module.  Low-Viscosity brake fluid is also preferred in cold climates, where standard brake fluid might become too thick in extreme below-zero temperatures.

You may ask what the difference is between wet and dry boiling points, and the answer is simple.  The manufacturer designated wet boiling point is the temperature at which the brake fluid will boil after it as absorbed exactly 3.7% water by volume.  It is generally understood that this is an acceptable amount for the average car to have before requiring a brake fluid flush.  The boiling point of wet vs dry brake fluid can be drastically different (for instance, the wet boiling point of Dot4 is a minimum of 311F, 135 degrees less!  That’s why it’s important for you to keep your brake system clean and fresh, you never know when you will end up on the back side of a very long hill, boiling brakes is something you never want to encounter.

I put together a kit that will allow you to flush your system with ease, the number for it is 000K10007.

eEuroparts Brake Fluid Flush Kit 000K10007

Please contact our customer service department at 800-467-9769 or for any of your brake service questions.



Posted in DIY How-To

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.