Have you ever inadvertently used DOT3 in a DOT 4 specified brake fluid system? Is it going to affect your braking system adversely? Should you immediately flush the DOT3 fluid out and start again?
Yes, it’s ok to use DOT3 brake fluid. The difference between DOT3 and DOT4 is the temperature of the brake fluid. On a performance motorcycle, you should use DOT4 brake fluid; DOT4 absorbs less water, so it won’t boil when hot.
If you mix them by mistake, they are compatible.
Can you use DOT3 in a motorcycle?
Yes. DOT3 is ok to use on a motorcycle and can be interchanged without a problem.
DOT3 will absorb more water from the atmosphere than DOT4; hence DOT3 has a lower boiling point. For most riders, the boiling point of brake fluid is not an issue. However, if you ride a performance motorcycle, it would be better to use DOT4 brake fluid.
A high moisture content in your brake fluid can be bad news for the motorcycle rider, and you may experience reduced stopping power under heavy braking as your brakes boil.
It is reported just a 3% moisture content in DOT3 will reduce the boiling point of the DOT3 fluid by 100 degrees, which is a lot when you consider how hot brake pads get, especially under emergency braking.
So while DOT3 is perfectly safe to use, it does have some drawbacks depending on what type of motorcycle riding you do. Also, consider the heavier your motorcycle, the more stopping power you need.
Never mix DOT3 with DOT5 brake fluid, DOT5 is silicon-based, and the two will not mix.
Can I use DOT3 instead of DOT4 motorcycle?
If your motorcycle was designed for DOT4 brake fluid, stick with it. DOT4 is ultimately a better brake fluid to use, and it is less hygroscopic than DOT3.
If you find yourself in a situation where your brake fluid is low, then go ahead and use DOT3. It will not harm your braking system.
Can I use car brake fluid on my motorcycle?
Cars use DOT3 and DOT4 brake fluid as standard, so you should be able to use them without a problem. There is one caveat you will need to check the viscosity of the brake fluid. Cars and motorcycles sold in extreme climates call for lightweight brake fluid. It will be designated LV.
LV brake fluid should not be mixed, but it will get you out of a pickle if needed and then flush your system with the correct fluid.
What brake fluid does a motorcycle use?
It’s best to use DOT4 brake fluid, it will last longer, and you are less likely to experience corrosion of your brake cylinders because it does not absorb as much water as DOT3 brake fluid.