The one feature your vehicle has that is very important is the brakes, without these functioning properly a serious collision or accident could occur. There are so many vehicle owners who may admit that they don’t keep a check on their vehicles brake fluid as much as they should.
Manufacturers themselves never seem to give out the necessary information regarding when to change brake fluid. As long as you check the fluid level and it is up then this is okay, changing the fluid when necessary can protect the braking system from corrosion.
There is some country’s for instance like Canada where the specifications of brake fluid come under regulation by transport Canada. They don’t actually define brake fluid but they set the necessary criteria it has to meet. For example, it has to be able to flow in cold weather, compatible with different components in the braking system, and boil at high temperatures. In the U.S.A, they too have similar specifications from the Department of Transport, (DOT), and the brake fluids are labeled as to how they meet different classes.
Many vehicle makers use DOT 3 type fluid although there may be some who prefer to use DOT 4 type fluid because this fluid has a boiling point that is higher. These two fluids are both glycol-based and are hygroscopic, this term simply put means they will both absorb water. If a container is left open, it absorbs moisture from the air, whilst the brake system, over years, will slowly absorb water through rubber hoses and other parts.
There is another brake fluid that is silicone based. This is classed as DOT 5.0 or 5.1 types. These fluids have a blue dye put in that makes it visibly different to other brake fluids. The advantage of silicone-based brake fluid is that it isn't hygroscopic and therefore won't cause damage to any painted parts; however, it will pass through smaller pores and won’t provide as good a seal.
The majority of vehicle manufacturers prefer to use DOT 3 fluid in their factories. Mixing two different types of fluids should never be done. Those who wish to use a silicone based brake fluid will have to clean the entire system of glycol-based fluid.
There are many who ask the question when should brake fluid be changed or flushed, there may be no definite answer as there are different opinions to this question. In the U.S.A, for example, research has been done by Maintenance Services Task Force of the Automotive Maintenance Services and Repair Association (AMRA) and the same opinion applies.
As mentioned before, water in brake fluid can cause corrosion, leaving deposits of sludge in the brake system. Many also believe that dark colored brake fluid should be changed to a light amber color. AMRA may surprise a lot of people with their surprise findings and for many sorts out the difference of opinion.
The myth regarding the color of brake fluid can quickly be solved in that this is not an indicator of the brake fluids quality. The color of several brake fluids can change naturally when the fluid is in contact with the brake systems rubber components. Tests that have been carried out shown that dark is still good and light amber fluid was poor.
Brake fluid is hygroscopic and having water in the brake fluid will lower the boiling point and therefore may not work as well. Water causes problems with corrosion but there are no tests available to check the water content of brake fluids. Through research, it has been found only a small amount of water is absorbed into the brake system. The rubber materials have improved greatly, therefore helping the seal to keep moisture out a lot better. The plastic see- through reservoirs limits the brake system being open to the air.
It is corrosion inhibitors in brake fluid that help to reduce breaking down of materials in the brake system. These inhibitors eventually wear out with age, water content, heat from the high braking system, and the copper in the brake lining will start to corrode. As the amount of copper ions build up in brake fluid, these act as oxidizers and other parts will begin to corrode. These can be the ABS valves and the master cylinders.
It is possible to check for copper content using paper strips that will change color if there is a high content of copper. Most service shops may use these but there may be some who don’t. If not, then they won’t actually know whether the brake fluid is good or should be changed. To be on the side caution in a situation like this, it may be better to have the brake system flushed and clean brake fluid put in. This can save you a lot of money as corrosion related repairs are very expensive and more important, you want to be sure your brake system stops works as you want it to.