Solvent Diluent: The solvent diluent determines the boiling point and viscosity of the braking fluid. Between 50% and 80% of the braking fluid is made up of it. Glycol ether is the most used solvent diluent. Castrol recommends that DOT fluid in previously opened containers should be discarded after 12 months. In our opinion it would be unwise to use DOT fluid from a bottle which has been open for more than a few months, unless you have no other alternative. For heavy-duty commercial vehicles, motorbikes, 4WD’s, and passenger cars, this brake fluid may be used to re-fill or top-up the clutch and braking systems. Agriculture, construction and mining equipment can all benefit from this fluid. However, the fact that it’s unregulated could be viewed as an advantage to the manufacturer because it means they have full control over the process of manufacturing their brake fluid.

Another con when it comes to this type of fluid is that it cannot be mixed with glycol-based fluids because it will not mix with them and also not deliver the performance you desire when you do so on your car. DOT2: DOT2 brake fluid has a dry boiling point of 190 degrees Celsius. The wet boiling point is 140 degrees Celsius. This is a mineral oil-based fluid and is rarely used in the automotive industry thanks to its relatively low boiling points. And what about the difference between DOT 3 and DOT 5 brake fluid? What is different between the two fluids and what are the pros and cons of each one?Make sure to cover any areas DOT fluid could leak onto with a rag because it’s corrosive. Matthew Allen / Immediate Media

The first thing that you will notice is the DOT 5 brake fluid color. The color of the DOT 5 brake fluid is purple. Unlike the glycol-based fluids which are usually clear in color and don’t have any coloring to them. The main difference between these two brake fluids is in their boiling points. Part of the standards that need to be met by the manufacturers of DOT fluids are the minimum dry and wet boiling points. These are the minimum temperatures that the brake fluid must perform at before the brake fluid starts to boil, which can lead to complete brake failure. What are the issues with having brake fluid filled to above the 'max' point - will a car fail an MOT with the fluid overfilled?;In fact, there are some modern DOT 4 brake fluids available that even offer higher boiling points than the DOT 5 brake fluid. So, it’s not advisable to switch to DOT 5 if you use DOT 4 brake fluid for your vehicle.

Since DOT 3 is glycol based, it absorbs moisture easily as well. As a result, DOT 3 brake fluid accumulates around 3% of water in it in a year.

The fluid was a low viscosity fluid based on diluted alcohol. [11] 49% alcohol 49% distilled water 1% triethanolamine phosphate ( surfactant) 1% sodium mercaptobenzothiazole ( stenching agent) Characteristics [ edit ]