DOT 3 VS DOT 4 Brake Fluid: Do They Mix & Which is Best? • Cars Simplified

DOT 3 VS DOT 4 Brake fluid... Do they mix? Is it better to use DOT 4? Steve discusses why people are quick to think that they don't, why DOT 5 doesn't mix, and why it is better to use DOT 4 brake fluid.

What is the best brake fluid and why? Between DOT3 and DOT4, the formulation of DOT4 is meant to deal with higher temperatures before boiling and is compatible with DOT3 systems, so DOT4 is better to use for both performance and life span improvements when used in a DOT3 system.

If you are looking for the absolute best brake fluid in the world, we will have a video in the future about that, but for the time being we will say that in most street driven modern cars, DOT 5.1 is the best, at least when this description was written. DOT 5.1 is designed to be compatible with DOT 3 and DOT 4 systems, but can handle more heat than those fluids. This will reduce the likeliness of brake fade occurring and in systems that are well-sealed, can even have a longer lifespan.

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[mannys]

You also have DOT 5.1 which is another glycol brake fluid. It's compatible with DOT 3 & 4 and has an even higher boiling point than DOT 4! Dry boiling point is 518*F and wet is 374*F. It's very important though that people understand that 5 is silicone and totally different than 5.1 fluid. That extra .1 makes all the difference in the name.

[MPGunther]

You answered my question, I topped off my brake fluid with DOT3 not realizing DOT4 was in the reservoir so I should have no worries when it mixes together

[rayklukoske]

Some misinformation in this video... DOT 4 does NOT have a longer lifespan. It does have a higher boiling point but it also absorbs water 20% faster than DOT 3 and needs to be changed more often.

[JD-imwu]

...added dot4 to my dot3 brake fluid then watched this video to feel more confident in my choice :)

[ridemfast]

Nice vid. For my motorcycle I use Bosch 5.1. LV and 3 year service interval. My Altima gets standard DOT 4 although it came with DOT 3.

[johnnyray]

Thank you for helping out you solved my question. I didn't know whether to use Dot 4 we're on my cap is marked Dot 3.

[wildmanofthewynooch]

Ok million dollar question here if my car requires DOT 3 but I want to use DOT 4 and then I take it the shop and they put DOT 3 in it to top it off is that a bad thing?

[skylinefever]

I use Pentosin DOT4LV in every ABS equipped car in my family. I figured that since they have ABS brakes anyway, I might as well use something that works well with the ABS. Pentosin is usually the cheapest and easiest DOT4LV to find. In cars that didn't have ABS, I used Valvoline DOT4 because it is extremely light in color. That color change makes it easy to see if the old fluid is out and the new fluid is in. Pentosin is an intense bright yellow, so it isn't as easy to see.
Honda used to claim that their fluid had a special lube in it to protect the master cylinder. I have had Pentosin DOT4LV in there since 2015, and 5 years later, there still hasn't been a problem.
Whatever you buy, don't buy the GM OEM DOT3. It gets dirty after one year. Basic DOT3 is better than the GM stuff.

[TomboRectify]

Hey please someone solve my problem: my scooter needs more brake fluid but I don't know which one it currently has. I would like it to have DOT 4 fluid but if it has DOT 3 fluid and I add DOT 4, will they mix, is it OK?

[matthieuratrimoson]

My question might seem stupid but, if my car initially had DOT3 brake fluid but can also take DOT4. I replaced the master cylinder and put in DOT4, can I revert back to DOT3 in the future?

[stevesun]

What is the best DOT 4 brake fluid in your opinion for a Honda Odyssey? Is it OK to replace old DOT 3 with Dot 4 in the brake reservoir without doing a flush or bleeding the brakes?

[stevesun]

What is your opinion of the Amsoil brake fluid. It says DOT3 & DOT4 on its label. Does that mean that you can: 1- top off existing DOT3 and DOT4 in my 2007 Honda Odyssey; and 2- top off existing DOT4 in my 2000 Volvo S80?

[matthewholzinger]

Glad to learn about this. I suspect shop that did my front brakes filled with DOT3 instead of the DOT4 that was called for. Idiots didn't bleed properly, broke both Front ABS cables and pedal went to floor. I had most of front end done and mgr was blaming it on the parts I supplied. Steering components don't effect the brakes. New calipers, pads and since all was being done front brake hoses too. I will never the apes at Car-X touch my car again. Blame the parts not their crap work.

[musicfashionstyle]

Can i use DOT 4 LV On my Acura Tsx 2009

[chasedavis]

Dot 4 has a higher boiling point, but it absorbs water a bit faster

[AndrewBrowner]

on my 05 jeep and my 96 dodge diesel after replacing some brake components calipers lines ect and filling with dot 3 ive had mastercylinder failures on both.. is it the fluid, is it something im doing while bleeding/filling? or is it just a coincidence and expected with the vehicle age

[Drewpb]

I have a ram 1500 manual says dot 3 recommend dot 4 acceptable....so would the valvoline 3&4 be a fantastic choice?

[rayslifek]

My bike says only use dot 4 and I put dot 3 am I

[mdfaisal]

can i fill dot 4 in dot 3 system mixing both fluid?

[luaymurad]

Thanks, , so why nissan say only use dot 3 brake fluid?