Brake fluid expiration date

Content

Reasons for the decline in quality
When to replace?
How to check the status?
How long does brake fluid keep in the package?
Recommendations for use and storage

Brake fluid is the key transmission material that distributes force from the pedal to the pads in a hydraulic system. During operation, the TJ absorbs moisture from the atmosphere. As a result: the boiling point and viscosity of the hydraulic fluid changes, and the brake system becomes faulty or ineffective. We will tell you about the expiration date of the brake fluid and storage rules, as well as give recommendations on how to increase the operating period.

Reasons for the decline in quality

The composition of the brake fluid includes polyglycols, boric acid esters, and Dot 5 contains poly-organosiloxanes (silicones). With the exception of the latter, all of the above components are hygroscopic. As a result of work, the material absorbs water from the air. Subsequently, the hydraulic system overheats, the fluid on the hydraulic pads heats up to evaporation temperature and forms a vapor lock. The brake pedal travel becomes non-linear and braking efficiency is reduced. Upon reaching 3,5% moisture by volume, TF is considered old, and at 5% or more, it is unsuitable for use.

The technical qualities of the liquid depend on the ambient temperature. The hotter the weather, the higher the humidity, and the TJ will quickly lose its performance.

Brake fluid expiration date

When to replace?

The manufacturer indicates the date of production, shelf life and operation on the container. The chemical composition directly affects the duration of application. For example, Dot 4 includes, in addition to glycols, esters of boric acid, which bind water molecules into hydroxo complexes and extend the service life up to 24 months. A similar Dot 5 lubricant, due to the hydrophobic silicone base, is slightly hygroscopic and can be stored for up to 12–14 years. Dot 5.1 refers to hygroscopic varieties, therefore, special moisture-retaining additives are introduced into it, which increase the shelf life to 2-3 years. The most hygroscopic liquid is Dot 3 with a service life of 10-12 months.

The average shelf life of brake fluid is 24 months. Therefore, it should be replaced at the first sign of a decrease in the efficiency of the brake system or after every 60 thousand kilometers.

How to check the status?

It is possible to determine the quality of hydraulic lubrication using a special tester. The device is a portable marker with a sensitive indicator. The tester is lowered into the tank with an indicator head, and the result is displayed in the form of an LED signal that indicates the moisture content. To maintain the operating temperature regime of the TJ (150–180 °C), the proportion of water should not exceed 3,5% of the total volume.

Brake fluid expiration date

How long does brake fluid keep in the package?

In a closed container, the material does not come into contact with air and retains its technical properties. However, over time, some compounds naturally degrade. As a result: the boiling point and viscosity of the product change. According to international standards, the shelf life of special fluids in unopened packaging, including brake fluids, is limited to 24–30 months.