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

[@mannys9130]

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.

[@CarsSimplified]

All correct! I think there is a DOT 5.2 now as well, and that will be the topic of another video if I can get my hands on some! Edit: 5.2 doesn't really exist, but 5 and 5.1 are still up for a future video!

[@rayklukoske9211]

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.

[@h2000l]

Basically DOT 4 is like high performance tires - very good when brand new but wears down quickly.

[@lonniebeal6032]

This is the 3rd time I've read this. Thanks.

[@14bqdonk]

​@@h2000lwell said

[@JeremypoythressPoythress]

It actually Lowers the boiling point and increases braking performance somewhat in lacking areas. Also absorbs water faster but is more viscous and flows better preventing build up and blockages in lines. Mainly used in high performance classic cars, going down steep hills where alot of braking is required,or applications requiring specifically dot 4. I don't use alot I just top off my master cylinder with it.

[@JD-im4wu]

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

[@cartersimataa7531]

Is it safe to add Dot 4 to Dot 3?

[@marshalllhiepler]

Yes.

[@shehabkg1383]

Thanks man!

[@6226superhurricane]

Dot 4 does not last longer, it more readily absorbs water. If you don't need dot 4, you're better off with dot 3.

[@AntonioClaudioMichael]

Thanks for the information

[@wildmanofthewynooch7028]

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?

[@CarsSimplified]

Slightly bad, but only in that you are dropping the boiling point just a little bit, assuming the DOT4 in there is still working at peak performance at the time the DOT3 is added.

[@cartersimataa7531]

My suzuki swift has a dot 3 on its cap.. The brake fluid is almost at the min level. I'm told to top up. Problem is I don't know what brake fluid is in the reservoir. They told me dot 3 is not avail so I bought dot 4. Is it safe for me to add it. Will there be a problem?

[@skylinefever]

DOT4 will work fine. If the reservoir is low, it is a sign that either you have no brake pad and disc material left, or you have a fluid leak that will soon get far worse.

[@cartersimataa7531]

@@skylinefever Thanx man

[@mdev8846]

@@skylinefever You are right.

[@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.

[@CarsSimplified]

Good stuff to know! I've got some Pentosin DOT4LV that I have been meaning to try out in my GTO before I start recommending it. Does it smooth out actuation of the ABS unit compared to non-LV fluid?

[@skylinefever]

@@CarsSimplified I don't think I have ever hit the brakes hard enough to activate the ABS, so I can't tell if it makes a difference. Also, for all I know, it makes a difference, but only enough to be seen on expensive diagnostic tools.

[@ridemfast7625]

In the future, Check out Bosch 5.1 ESL. 3 year service interval, low LV.... Cost less the Pentosin also.

[@skylinefever]

@@ridemfast7625 That sounds great. I'll keep an eye out.

[@MPGunther1]

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

[@CarsSimplified]

As long as DOT 3 is approved for that vehicle, yes. If the car needs the heat resistant benefits of DOT 4, then adding DOT 3 will drop the boiling point a bit below the requirement.

[@ridemfast7625]

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.

[@dontblameme6328]

Good for you!

[@stevesun100]

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?

[@CarsSimplified]

Well, it meets DOT4, so it's at least that good. Unless it says not to, it should mix with any other DOT3 or DOT4 fluid. It should work for you in both cars. For any above and beyond quality for any brand comparison, a good place to start is by comparing wet and dry boiling points. I have no experience with Amsoil brake fluids, but they tend to make good stuff.

[@user-n6r7y]

Awesome video!! New subscriber

[@aryanprivilege9651]

I’m gonna put jumbo jet 747 brake calibers rotors, assembly, and fluid if can move then. Both in my motorcycle and personal vehicles, what if I’m carrying 1,000,000 lbs you don’t know me! I’m attaching wings and jets to everything while it’s still legal maybe! 😃 Strive for excellence, life is struggle! HH. PS I litter to as a scofflaw, so heads up!

[@joemartinez6182]

I mixed dot four to my ford ranger by mistake as it takes dot three but it seems like its ok, I didn't add a whole lot but I was wonder>

[@CarsSimplified]

DOT 4 and DOT 3 should be compatible, but you won't see any of the DOT 4 benefits until the DOT 3 is flushed out.

[@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?

[@matthieuratrimoson3271]

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?

[@CarsSimplified]

Not a dumb question at all! You should be able to switch/mix back to DOT3 (as long as both the DOT3 and DOT4 aren't lying about their DOT rating, but as long as you're sticking with familiar brands and retailers, that shouldn't be an issue). I would suggest sticking with DOT4 since it should be better in every way, but going from DOT4 to a partial or full DOT3 should be fine as long as you expect DOT3 performance out of the mix.

[@matthieuratrimoson3271]

@@CarsSimplified thank you I have one more, it might be dumb again, if you don't mind. Since DOT4 has a higher boiling point than DOT3, is it normal to feel a slight difference in the brake pedal? All air have been correctly bled out of the brakes and master cylinder. Thank you

[@CarsSimplified]

That can happen, and it can even happen when switching to fresh fluid of the same DOT type and/or when brake components have been replaced. Just make sure everything is working properly, because sometimes fresh fluid may flush out a blockage that was plugging something up, be it a leak or passageway.

[@matthieuratrimoson3271]

@@CarsSimplified thank you so much for clearing this up!

[@rayslife4k]

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

[@CarsSimplified]

It probably needs the added heat tolerance of the DOT 4. With DOT 3, they will still function, just less effectively when they get hot. That happens under hard braking, when you need it most, so even if you did some typical riding and it seems normal, I'd still replace the DOT 3 with DOT 4 for safety.

[@mdfaisal216]

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

[@CarsSimplified]

As long as the fluid in there is good, they will mix, but the DOT3 will end up at the end of each line, where the heat is highest. You will see almost no benefit until the DOT4 fluid gets all the way to the calipers.

[@iglesiasalberto3]

When in Philippines is it ok to use dot 4f?

[@elbotas6097]

Thanks your for your info. 👍🏽

[@AntonioClaudioMichael]

Great video

[@matthewholzinger1042]

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.

[@mdev8846]

The best fluid brake DOT 3 is AP RACING R1.

[@linkbond08]

I guess get cheaper dot 3 in bulk and service your brakes like you're supposed to.. I was wondering why to use a extremely corrosive liquid as brake fluid, instead of hydraulic oil, for some other non-destructive liquid, but I guess you need some kind of special liquid with very high boiling point.. makes sense.

[@mdev8846]

You are right. DOT 3 brake fluid is used as cluth fluid too. Be careful !.

[@gotitdone]

Agree. I would like to caution not to buy too much since opened bottles will collect water from the air over time. So buy only what you will use during the job and return any unopened bottles.

[@linkbond08]

@@gotitdone I usually flush my brakes from fardest one to closest one until clear liquid comes out then, flush the fardest one again, by then I'm out of the quart bottle.

[@gotitdone]

@@linkbond08 Yes. 32oz is always short. I need around 40oz to flush my brakes. All my three Hondas use dot3 and currently Walmart is selling Prestone dot3 Max (100k miles) 32oz for $10, so I buy 4 of those. There is no gallon of it. These cars are driven around 20k miles per year

[@johnnyray88]

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.

[@stevesun100]

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?

[@CarsSimplified]

In regards to the topping off, while you can do it, you won't see any benefits from better brake fluid of any kind unless it flushes out all the bad fluid, so a flush is required for any improvement to happen.

[@marshalllhiepler]

In the future, we'd prefer to speak directly to Steve when possible. We realize that you are his sun, but there is less chance of miscommunication if we interact with your dad without a middle-man. Thanks.

[@makineedidorababu3329]

Can i use dot3 and dot 4 same time

[@CarsSimplified]

As long as you're sure that's what they are and you're sure they're both in good condition.

[@luaymurad5239]

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

[@CarsSimplified]

Well, it has to specify brake fluid, as well as a type, and it can't say "DOT 3 or higher" because of DOT 5 won't work. It may need to be labeled with the factory fill fluid and printing "use DOT 3 or DOT 4" would cause service issues; if a brake failure occurs after a mechanic fills a "DOT 3/4" car with DOT 3, then it becomes a "Why didn't you fill the car with the better brake fluid?" situation, so any car with a "DOT 3/4" cap would only be filled with DOT 4 to avoid that scenario.

[@maca25]

Can i use dot4 for toyota rav4 2017

[@chasedavis2358]

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

[@musicfashionstyle9269]

Can i use DOT 4 LV On my Acura Tsx 2009

[@Drew858pb]

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

[@mdev8846]

Recommend is better that acceptable...

[@DickiMonster]

The guy from donutmedia

[@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

[@AndrewBrowner]

failures as in its pushing the fluid back to resevoir causing pedal to be kinda soft/squishy, new MC's are ordered

[@CarsSimplified]

I would make sure the master cylinder is indeed having an issue; it's unlikely that two of them would fail at the same time. Air in the system typically causes what you're describing, and the more brake hydraulic components are replaced, the more likely it is that air found its way in. The seals in the master cylinder can go bad from really contaminated brake fluid, but that doesn't wait for new fluid; it wears gradually.

[@AndrewBrowner]

@@CarsSimplified well it was several months apart but both a couple weeks after major break surgery, the air was all out and brakes performing good very solid peddle for a couple weeks before issue, the dodge anyway felt on a braking attempt like a hose snapped and peddle suddenly lost its solid bottom, checked everywhere no fluid leaks and no fluid missing after a few days of driving, when someone is pushing down the peddle an see a stream of fluid pushing up to the top of the reservoir making a ripple in the surface.. i suppose its basically free to bleed them all again only take 10 minutes but im pretty sure its the MC, just curios if theres anyway to mess up there thatd cause that or if mixxing the fluids is bad but it seems dot3 and dot4 are both fine and i think the vehicles call for dot3 anyway, didnt check tbh i bought a gallon jug of dot3 so i always use that

[@CarsSimplified]

How long has it been since that gallon of fluid was first opened? Brake fluid often ages poorly because it absorbs moisture out of the air and that would cause a soft pedal when the fluid gets hot, but only when it gets hot.

[@AndrewBrowner]

@@CarsSimplified its all the time and was a very sudden occurrence on the dodge i was sure a flex line busted, and opened the fluid in late fall so like 6months or so, i fill up a smaller container so i dont have to open the gallon constantly so it stays sealed with less fresh/humid air entering.. thanks for the replys and discussion im sure it was just a coincidence, MC was overdue anyway it looks factory on the 96 with 570,000kms

[@ohhgeez865]

Thank you!

[@JD-im4wu]

Excellent review! Subscribed!

[@Soliloquy1972]

Thank you!

[@GobiAtanari]

thanks for explain, one question, can we use power steering fluid for brake oil?

[@gotitdone]

NOOOO! Don't do that. Don't mix them up. You will ruin the brake lines and it will be an expensive and unnecessary repair.

[@GobiAtanari]

@@gotitdone thank you

[@mikuizayoi824]

Always refer to manufacturer specification for the right brake fluid for your vehicle so don’t change your brake by watching you tube people. Not having the correct brake fluid can cause failure to brake systems or worse can kill

[@mdev8846]

You are right. The problem is a lot of cars have DOT 3 specs and today this brake fluid is disappearing.

[@steveretiredandcranky]

Start with a simple "yes" or no and then explain.