DOT 3 vs DOT 4 Brake Fluid (What’s the Difference?)

There are two main different types of brake fluid that are used by most auto manufacturers. There is DOT 3 brake fluid and DOT 4 brake fluid. Here are the main differences between the two types of fluid.

  • Boiling Point

DOT 4 brake fluid has a higher boiling point than DOT 3 brake fluid. If you tend to do a lot of heavy braking with your vehicle, then DOT 3 brake fluid could easily boil which would result in the complications noted above.
Dot 4 brake fluid is more reliable when you’re regularly doing a lot of heavy braking because it doesn’t boil as easily. Car owners who are involved in autocross or lapping days at the track will definitely require a brake fluid with a high boiling point.

  • Chemical Components

DOT 3 brake fluid is made from the ether and polyalkyelen glycol being mixed together. This mixture creates a brake fluid that can handle wet conditions and average heated conditions.
DOT 4 brake fluid is made of borate and glycol. This mixture makes the brake fluid more stable and able to handle higher temperatures.

  • Car Types

The average economy car will use DOT 3 braking fluid because in general, the cars require less stopping power and the driver won’t be braking aggressively very often.
However, you can expect to see DOT 4 braking fluid in police cars, motorcycles, and racing cars; since they all brake more frequently and aggressively. Always follow the vehicle manufacturer’s recommendation as to what type of brake fluid to use.

  • Boiling Capacity

DOT 3 braking fluid contains both a great wet boiling capacity and dry boiling capacity. This means the fluid will work well when it’s exposed to water and the open air.
DOT 4 braking fluid is best when it comes to a dry boiling capacity. Unfortunately, its wet boiling capacity is not so great.

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