The market right now has several options for brake fluids. They include DOT3, DOT4, DOT5, and DOT5.1. All these brake fluids will help you brake better if you always use the right brake fluid for the vehicle. However, can you mix the DOT 3 and DOT 5 brake fluids?
It is important to understand that these two brake fluids are made of different materials. These different ingredients do not mix; thus, the reason you cannot mix DOT 3 and DOT 5 brake fluids. Sticking to one brake fluid to ensure the best performance rather than mixing them is best.
What is DOT 3 Brake Fluid?
Understanding DOT3 brake fluid can help you see why mixing it with the DOT5 brake fluid would not be good.
The DOT3 brake fluid is a polyethylene glycol-based brake fluid designed to withstand very cold and hot temperatures without necessarily thickening. So, even if you keep driving for hours, this brake fluid would withstand the temperatures better.
The typical boiling point for DOT 3 brake fluid is 250 degrees Celsius. This would give the brake fluid a wide range of applications where such a type of fluid is necessary.
As for the color, the DOT 3 brake fluid is mostly yellow to amber and will have a mild glycol odor. It is not something you can miss compared to the DOT5 brake fluid, which has a different look.
DOT3 brake fluid is also hygroscopic. This means that it is slightly soluble in water. The water being part of the brake fluid would make it have degraded performance. That is why you should always have the cover of the brake reservoir tightly fitted to avoid such cases.
Another reason for picking DOT3 brake fluid is because it comes with excellent corrosion protection. The result is that your braking system would now last longer without necessarily having to replace parts anytime soon.
Here is a video with more details about DOT3 brake fluid and how it differs from DOT 4 brake fluid.
What is DOT 5 Brake Fluid?
When the DOT-3 brake fluid is glycol-based, the DOT 5 brake fluid is silicone-based. This is the most significant difference between these two brake fluids.
Since it is silicone-based, DOT 5 brake fluid does not absorb moisture. This means it can maintain its overall chemical composition and work as it should. So, for those who want to prevent the potential buildup of rust in the braking components, the DOT 5 brake fluid is the right one for you.
How about the color? While DOT 3 and DOT 4 are yellowish in color, the DOT 5 brake fluid has a purple color. It becomes quite easy to tell the difference between these two options. Also, it would be hard to mix the two when you can visually see they are different.
DOT 5 brake fluid also has a higher boiling point than the DOT 3 brake fluid. It has a boiling point of 500 degrees Celsius. You can see that this high boiling point means it can always handle hard braking. That is why it would be used mostly in racing cars.
The cost difference can also determine which one you choose for your vehicle. DOT3 brake fluid can cost up to $15, while DOT 5 will cost as high as $45. This can make more people consider DOT 3 since it works just as well for normal driving and is not as expensive.
Should you switch to using DOT 5 brake fluid?
DOT 5 brake fluid should be used only in rare circumstances. Keep in mind that once you start using DOT 5 brake fluid, there is no using the other types available. This is because it is hard to remove all the DOT 5 brake fluid despite how much you flush the brake system.
Still, DOT 5 is not compatible with cars that have ABS. Considering all modern cars are mandated to have ABS, they remain incompatible with the DOT 5 brake fluid. This is because this brake fluid can become frothy with time as you keep pressing and releasing the brake pedal, and ABS is involved. The result is that you may end up with a spongy feeling of the brakes.
Also, DOT 5 brake fluid would need extra maintenance, or else you might end up with rusted brake system components.
Here is a video with more details on DOT 5 brake fluid
Can you mix DOT 5 and DOT 3?
No. This is not recommended as these two are made of different ingredients that cannot mix. The DOT 3 brake fluid is glycol-based, while the DOT 5 brake fluid is silicon-based.
Can you mix DOT 5 and DOT 5.1?
Despite having almost similar names, you should not mix the two as they have totally different chemical components. The DOT 5.1 is gylcol-based, while DOT 5 is silicon-based. Always look at the chemical ingredients before mixing any brake fluids.
Which brake fluid can you mix with DOT 3?
DOT 3 can only be mixed with DOT 4 and DOT 5.1 brake fluids. This is because they are glycol-based fluids. They would not generally harm the rubber parts of the brake system when mixed. We, however, recommend only using one type of brake fluid for the best performance.