As you probably already know, the braking system of a vehicle is a critical safety system that prevents the likelihood of dangerous accidents and hazards. However, what many vehicle owners do not know is that the braking system of their car becomes a lot more critical when it comes to performance and race applications.
A considerable amount of heat is generated to bring your vehicle to a stop. The amount of heat created will be relatively higher in heavier vehicles. In addition to that, heat produced to bring faster vehicles to a stop will also be significantly higher. Therefore, the brake fluid in your vehicle should be able to withstand the heat while it is serving the crucial purpose of transferring force from brake pedals to the wheel cylinders or calipers.
The brake fluid commonly used in modern day vehicles will have to meet certain standards in order to ensure the safety of drivers. These standards are usually set by the Department of Transportation (DOT) and the Society of Automotive Engineers (SAE). Based on these standards, brake fluids are often classified as DOT 3, DOT 4, DOT 5, and DOT 5.1.
Most car owners are not aware that DOT 3, DOT 4, and DOT 5.1 brake fluids are actually glycol based while DOT 5 is silicone based. Most of the glycol based brake fluids available in the market are hygroscopic, which means that they absorb moisture from the air and gradually disperse it through the entire braking system.
The boiling point of glycol based brake fluids will decrease as the water content in it increases. As a result, the extra moisture in DOT 3, DOT 4, DOT 5.1 brake fluids will gradually start to corrode the metal components of a braking system. An important aspect to note is that silicone and glycol based brake fluids are not compatible with each other.
On the other hand, the silicone based brake fluid DOT 5 does not absorb moisture readily from the air. Instead, the pockets in these fluids boil off or freeze the moisture that is introduced into the system. This could cause severe damage to the brake system in long run though, and may even result in brake failures, especially when used in regions that are known for higher humidity levels. This is one of the major reasons, why many car owners are somewhat hesitant to invest in silicone based brake fluids.