Synthetic Brake Fluid

In order to understand synthetic brake fluid, it’s important to know how brakes work, what brake fluid does, and what makes synthetic brake fluid stand out. Brake fluid, as we all know, plays an integral part in the breaking process, but few people know exactly how it works or how the overall process of braking happens. Between our pressing the brake pedal and the car actually starting, there is a very complex system designed to multiply the pressure we place on the brake pedal and place that pressure onto the car’s wheels.

Most modern cars use hydraulic brakes, as opposed to the drum brakes of days past. Drum brakes work in a similar way to bicycle brakes, where the pressure on the pedal more directly works to stop the car. However, they are almost never used as the main brakes anymore because they simple don’t work as well as hydraulic brakes (also known as power brakes). Hydraulic brakes use a combination of power brake boosters and brake fluid to apply pressure to the brake pads, which do the actual grinding that slows down or stops the vehicle. The brake fluid is brought into play in between the power booster and the brake pads.

A power brake booster works by creating a vacuum when you press on the brake. Without this, stopping the car would be impossibly hard. The brake fluid transfer the pressure created by this process. The brake fluid is needed here because it is not compressible, so the pressure is allowed to interact directly with the pad. Without brake fluid, or if your brake fluid is low, that pressure will dissipate, and the car won’t stop as well, because the pressure is no longer being applied to the pads, at least in full.

No liquids are really compressible, but brake fluids are designed to meet specific standards that keep them working in cars when other liquids might not. For example, brake fluids are made to be extremely resistant to cold, whereas if you were to use water, for example, it would freeze in the lines, and you’d likely rupture your brake fluid lines. Brake fluid must meet federal standards in regards to staying at about the same viscosity (or thickness) within pretty much any temperature that you’ll possibly meet. In low temperatures, it must not get thicker, and at high temperatures, it has to have a very high boiling rate, because the fluid can get very hot.

Synthetic brake fluid refers to, typically, brake fluid made out of some silicone substance. Most brake fluids are mineral based, which is typically what is sold. The argument can be made that all brake fluids are synthetic, but when brake fluid is called synthetic, that means it is silicone based. When you look at the container of synthetic brake fluid, you’ll usually see advertisements reassuring you that it is compatible with your car, or that it lasts just as long as regular brake fluid, or something of that nature. This is because most brake fluid is mineral based, so makers of synthetic brake fluids need to reassure their customer that their product will indeed work well.

The fact of the matter is that, in terms of actual performance, it will really make no difference whether you use synthetic brake fluid or not. What makes much more difference is the type of brake fluid. The main types of brake fluid are DOT3, DOT4 and DOT5. The first two can absorb water, which is generally a bad thing, while the latter doesn’t. In general, DOT5 is the best quality, whether it is synthetic or not.

There Are 2 Responses So Far. »

  1. I'm sorry but after reading the first few paragraphs of this articles i have to comment. The Author is drawing a distinction between hydraulic brakes and drum brakes. That distinction should be Drums brakes or disc brakes or Air vs hydraulic. There are plenty of hydraulic drums brakes on cars. he also mentions Power brakes being a hydraulic thing but anybody who's is in the automotive industry knows thee are plenty of old hydraulic brake systems that don't use a booster. Later you discuss the "difference" between synthetic and regular brake fluid saying synthetic means silicone based this is not accurate either. all brake fluid is synthetic and many manufactures are starting to label them as such because synthetic is a nice buzzword that markets well. at least your final paragraph does accurately sum up brake fluid but the poor examples prior to it are misleading to those not informed of how car brakes actually work.

  2. Most importantly warn people to never mix or put the incorrect break fluid in their car. You cannot put DOT 5 Break fluid in a car that uses Dot 3 or Dot 4 or you will experience brake failure which will most likely be fatal. Do not even mix Dot 3 with Dot 4.