As it can be confusing determining the appropriate brake fluid type for your car, knowing its DOT rating (Department of Transportation) rating will help.
DOT ratings provide information about the dry and wet boiling points of brake fluids. When mixing two fluids that contain glycol-based DOT 3 or 4 with silicone based DOT 5, it could cause serious damage to your brakes.
Identify The Correct Brake Fluid Type
Replacing brake fluid regularly is vital to ensure the safety of your car, but many owners may be unfamiliar with all of the different kinds of brake fluid available.
Brake fluid is an integral component of a vehicle’s braking system, converting mechanical pedal pressure to hydraulic pressure within the brake calipers, as well as keeping everything lubricated and protected against corrosion.
DOT Ratings
A brake fluid’s DOT rating is one of the primary indicators of its performance. This rating refers to its minimum boiling point.
Higher DOT ratings signify greater resistance to moisture absorption of brake fluid. Since brakes and clutches produce high temperatures during braking, it is crucial that their fluid can handle such temperatures without absorbing too much moisture.
High DOT rating brake fluid is ideal for vehicles which experience heavy load conditions such as towing trailers or driving through mountainous regions, while their higher DOT rating ensures it won’t overheat under demanding driving conditions.
Fluid Specifications
As part of your car maintenance needs, there are various levels of brake fluid specifications – these are: DOT 3, DOT 4, and DOT 5.1.
Your vehicle’s DOT rating relates to its fluid’s boiling point, which must prevent it from vaporizing and diminishing effectiveness. A higher boiling point will likely be needed for vehicles with greater performance capabilities.
Glycol-based DOT 3 is typically light amber in color and suitable for most passenger cars. It can be mixed with glycol-based DOTs 4 and 5, though silicone-based DOT 5 must always remain separate – it has a higher boiling point to handle more intensive use without becoming hydroscopic (absorbing moisture/water) while not harming paint finish on your car like its glycol counterparts can.
Synthetic
No matter their DOT rating (DOT 3, 4, or 5), synthetic brake fluids use glycol ether and borate ester compounds as the basis. This has been around for 50 years and provides a stable base for their production.
Traditional brake fluid can absorb moisture, lowering its boiling point and leading to corrosion of metal components of your braking system. Synthetic fluids have been specially engineered to be less hygroscopic and maintain their high boiling point even when exposed to moisture contamination.
Consult your owner’s manual to ascertain which DOT classification best applies to your car, then think carefully about how you plan on driving it and choose an appropriate type of brake fluid – for everyday commuting or highway driving, perhaps synthetic fluid from DOT 4 may suffice.
Mineral
Mineral brake fluids are unregulated, thus not subject to the same quality control measures as DOT fluids, giving companies like Shimano and Magura more freedom when producing custom products tailored specifically for their braking systems.
As such, mineral brake fluid tends to be slightly more costly than its DOT counterpart; however, as it is non-corrosive to paintwork it shouldn’t pose too many problems if some spills on your components accidentally.
Mineral oil tends to be less hygroscopic than its DOT 3 or 5.1 counterpart, enabling it to last longer without absorbing too much moisture into your braking system, leading to spongy pedal travel or corrosion of calipers. This will extend its usefulness.
Compatibility Of Brake Fluids With ABS Systems
Your choice of brake fluid will have a tremendous effect on the performance of both your car’s braking and ABS systems. Common choices in cars include DOT 3 or DOT 4, both made up of glycol-based amber fluid that absorbs moisture from the atmosphere to avoid corrosion issues in brake lines.
ABS systems do not play well with traditional brake fluid grades such as DOT 5, which contain precipitants which clog braking systems if mixed together. To counter this, two new grades were developed – DOT 4+ and 5.1 ESP – with lower viscosity than traditional DOT 4, yet still providing high wet/dry boiling points with reduced moisture absorption rates.
High-Performance
If your high-performance street or racing car requires extra heat resistance from higher dry boiling points, there are various solutions available to prevent brake fade and vapor lock. While meeting DOT standards, these high-performance brake fluids feature special compounds and chemicals with increased heat resistance ratings for greater dry boiling point ratings.
Most cars use either DOT 3 or 4 which is amber in color and glycol-based, with both types absorbing moisture out of the air (hygroscopic). As these fluids must be regularly replenished due to hygroscopic properties, race car drivers and others with high performance vehicles should consider switching over to DOT 5, which features reduced annual absorption rate as well as enhanced temperature performance.
Conclusion
Selecting the right brake fluid for your car is crucial for maintaining optimal braking performance and safety. Regularly replacing your brake fluid and ensuring you use the correct type for your driving needs will help prevent brake fade, corrosion, and maintain the overall efficiency of your braking system.
