Additionally, if your vehicle isn’t designed for DOT 5 brake fluid and you try to use it even after a full flush. You might still end up with a problematic brake system. This way you will get the best performance from the fluid when it comes to the dry boiling point temperature which will be 446 degrees when it comes to installing a new fluid, while if you mix it, you will only get a wet boiling point performance of 311 degrees which is not that good after all. DOT 5 brake fluid is typically much more expensive than DOT3 or DOT4 brake fluid. It can cost up to five times as much as your standard brake fluid for a bottle. This price difference isn't huge, but it is a definite difference between the two types of fluid. To reduce large quantities of wasted brake fluid, use DOT fluid from smaller 100ml bottles. 100ml is enough to bleed a set of brakes (front and rear) 2-3 times.

Due to their glycol-based nature, you may use the same DOT 4 lubricant with DOT 3 and DOT 5.1 without affecting performance or damaging the brake system. DOT 3 brake fluid has less rubber component expansion, which reduces fluid loss and leaks. Additionally, the braking system’s components are better protected against corrosion, increasing their dependability and lifespan. DOT 5 brake fluid (not to be confused with DOT 5.1) is fundamentally different than the rest of the DOT fluid range in that it is silicone based brake fluid.When it comes to changing from one to another fluid we would not recommend you to do so. Even though it is possible to do this type of work on your car. There are four types of braking fluid: DOT 3, DOT 4, DOT 5.1, and DOT 5. As kinetic energy is converted to heat by brakes, brake fluids are subjected to a fair degree of heating. Source:Apel USA It is also more compressible than the other DOT brake fluids which can lead to a sluggish or spongy brake lever (or pedal) feel, and therefore requires special design considerations when used in brake systems. Glycol based fluids are hygroscopic which means they absorb water/moisture from the environment at normal atmospheric pressures at a rate of 2-3% per year. This process is exasperated in more humid conditions and climates. But still, the core of this type of fluid is rather the same. The only difference is the color as well as some characteristics of this specific fluid that allows it to withstand more pressure and deliver good performance under extreme heat. Because brakes are getting really hot under heavy braking and even in normal use.

Brake fluid performance in extreme temperatures is the primary concern of the standards. As part of its criteria, they require that the fluid makers conform to a set of minimum boiling temperatures. DOT 4 and DOT 5.1 are both glycol-based brake fluids and are used widely in the automotive and cycle industry. They are controlled by standards set out by the Department of Transportation (DOT) - hence the name. Although DOT 5 Brake fluid comes with high boiling points and performs well in extreme temperatures. It’s more compressible than the DOT 4 and any other type of brake fluid that’s based on glycol ether.Glycol-ether (DOT 3, 4, and 5.1) brake fluids are hygroscopic (water absorbing), which means they absorb moisture from the atmosphere under normal humidity levels. Non-hygroscopic fluids (e.g. silicone/DOT 5 and mineral oil based formulations), are hydrophobic, and can maintain an acceptable boiling point over the fluid's service life. Ideally, silicone fluid should be used only to fill non-ABS systems that have not been previously filled with glycol based fluid. Any system that has used glycol-based fluid (DOT 3/4/5.1) will contain moisture; glycol fluid disperses the moisture throughout the system and contains corrosion inhibitors. Silicone fluid does not allow moisture to enter the system, but does not disperse any that is already there, either. A system filled from dry with silicone fluid does not require the fluid to be changed at intervals, only when the system has been disturbed for a component repair or renewal. The United States armed forces have standardised on silicone brake fluid since the 1990s. Silicone fluid is used extensively in cold climates, particularly in Russia and Finland. And this is for a reason, the DOT 5 is a silicone brake fluid. This means that it is not produced from the same compounds as the DOT 3 and DOT 4. Most brake fluids used today are glycol-ether based, but mineral oil ( Citroën/ Rolls-Royce liquide hydraulique minéral ( LHM)) and silicone-based (DOT 5) fluids are also available. [1] Standards [ edit ] Note: Do not mix with DOT 5 brake fluid but can be mixed safely with other DOT 3 and DOT 4 fluids. Features & Benefits: DOT 3, DOT 4, DOT 5, and DOT 5.1 are brake fluids named according to their boiling points– with DOT 3 having the lowest boiling points and DOT 5.1 having the highest boiling points among these fluids.

Since Mineral Oil is hydrophobic and does not absorb water from its environment, one of the great advantages it has over DOT fluid is that once opened it can be stored indefinitely.DOT 5 brake fluid is a silicon-based fluid . This was developed to be used in cars where moisture was definitely going to be prevalent and unavoidable. That means things like high performance vehicles and military vehicles. It has a very high boiling point, but it also has more compressibility than the glycol ether-based fluids. Also, there are now DOT4 brake fluids that have boiling points that are actually above DOT 5 brake fluid so there aren't a lot of reasons for you to look into getting a DOT 5 fluid for your car if you don’t need it. If you’re using DOT 4 brake fluid, you can switch to DOT 3 but not the other way around. While DOT 3 and DOT 4 are intermixable, mixing them together isn’t advisable because it can degrade the overall performance of your brake system.