DOT 3 vs DOT 4 Brake Fluid
- Thread starter JWC86
- Start date
Nope, both are polyethylene glycol based, just 4 has a higher boiling point when new.
Ok thanks, for this grocery getter I will just pick up some DOT 3.
And a higher boiling point when old, or “wet”.
Yes but that's based on it being saturated to a certain point, DOT 4 and DOT 5.1 is apparently more hygroscopic than most DOT3 and is likely to absorb more water long term, in a system that's serviced frequently 4 or 5.1 is probably a better choice but in most road cars where the brake fluid is touched on very rare occasion, it's hard to say which is really better.
DOT 4 has a higher boiling point, but it's more important to change the fluid regularly than what kind you actually use. Even Walmart brand DOT 3 is good to use. They also have a house brand DOT 4 that is a a good price.
Bosch ESI6 claims to have a longer life, but it does cost more. Another good choice is Castrol brake fluid that is supposed to absorb moisture more slowly; it used to be called LMA for "low moisture activity"
Bosch ESI6 claims to have a longer life, but it does cost more. Another good choice is Castrol brake fluid that is supposed to absorb moisture more slowly; it used to be called LMA for "low moisture activity"
The best brake fluid to use is a container you just bought, vs one that is half used and been on a shelf for months/years.
https://prestone.com/product/prestone-max-dot-brake-fluid/
$9.99 at autozone for the DOT3 version. 100k service life.
Modern brake systems really don't absorb moisture in the same way as older systems, especially the ones that are factory filled with DOT3. Fluid requires replacement due to degradation of the corrosion inhibitors, not moisture.
$9.99 at autozone for the DOT3 version. 100k service life.
Modern brake systems really don't absorb moisture in the same way as older systems, especially the ones that are factory filled with DOT3. Fluid requires replacement due to degradation of the corrosion inhibitors, not moisture.
Use Valvoline DOT 3/4 and you won't have to loose sleep over this conundrum.
Kokopelli34179
$50 site donor 2022
Use either one, your car will be happy.
For me, 4 wheel vehicles get DOT 3 or the DOT 3/4 fluid since I don't change those as often.
On my motorcycle, I use DOT 4 since it gets changed on a more regular basis (at least every 2 years, sometimes sooner).
On my motorcycle, I use DOT 4 since it gets changed on a more regular basis (at least every 2 years, sometimes sooner).
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My understanding of the "magical" Valvoline DOT 3 and 4 fluid is that it is just DOT 4 fluid in the bottle. That is because brake fluids are backwards compatible. In other words, if your car is designed for DOT 4, you don't want to use DOT 3. But if you car is designed for DOT 3 then you can use DOT 4. The reason it say "DOT 3 and 4" is to make it easier for average consumers when they are shopping for brake fluids.
There is one drawback with DOT 4 over DOT 3. DOT 4 is considered as "better" in performance but because of that, it will require more frequent change than DOT 3 as it is more hygroscopic.
There is one drawback with DOT 4 over DOT 3. DOT 4 is considered as "better" in performance but because of that, it will require more frequent change than DOT 3 as it is more hygroscopic.
Your Hyundai Tuscon will never reach brake temperatures that will require DOT 4. You will see no difference in performance between 3 and 4 except that 4 will have a shorter service life. It's a little strange that people are recommending the use of 4 depending on climate when it will have absolutely no appreciable difference. They are both hydraulic fluids in a hydraulic braking system and work on the basis of hydraulics. Liquids cannot be compressed. Dot 4 is used in high heat and high performance applications because boiling from intense braking aerates the liquid and creates sponginess, degraded brake performance, or a pedal that goes all the way to the floor. Because air can be compressed.
I strongly encourage you to stick with the recommended DOT 3 fluid for your passenger car.
I strongly encourage you to stick with the recommended DOT 3 fluid for your passenger car.
Well, not really if that's what the cap says. I decided to use DOT 3 as it doesn't absorb water as quickly as DOT 4. I can't imagine me
needing a higher boiling point brake fluid, even in the IS350. As far as one brand over the other, some people say all DOT 3 is the same.
I don't think it is. My understanding (not an absolute truth) is there is a DOT 3 minimum spec that all DOT 3's must meet. But some DOT 3's have a few more goodies added to them. Hey, what do I know? I stick with Toyota in all my cars.
needing a higher boiling point brake fluid, even in the IS350. As far as one brand over the other, some people say all DOT 3 is the same.
I don't think it is. My understanding (not an absolute truth) is there is a DOT 3 minimum spec that all DOT 3's must meet. But some DOT 3's have a few more goodies added to them. Hey, what do I know? I stick with Toyota in all my cars.
edyvw
$50 site donor 2025
The most important thing is to change fluid regularly. Those living in flat areas are the ones to say that fluid doesn’t need to be change that often. However, quick trip to the Rockies might give them different view of how important regular changes are regardless whether is it 3 or 4.
DOT4 are going to have higher boiling point, and some will have wet boiling point so high that won’t be much lower than minimum dry boiling point of DOT3.
All my vehicles get DOT4 ATE TYP200.
DOT4 are going to have higher boiling point, and some will have wet boiling point so high that won’t be much lower than minimum dry boiling point of DOT3.
All my vehicles get DOT4 ATE TYP200.
I'll add my data point here. I purchased a 2018 kia optima with 30k in December. Every service was documented on CARFAX, car was just about 2.5 years old. I was disappointed in the brake stopping power at higher speeds. No confidence. I re-bed the pads and that did nothing.
The pads still looked meaty but I figured I'd change them out as well as the rotors. I ordered both.
Before doing the brake job, I wanted to flush the fluids and bleed. I bought the motiv hydraulic valve on amazon to assist in the one man bleed job (awesome tool). I flushed with generic DOT 3/4 fluid from RA. The brake performance is night and day. The car actually wants to stop at higher speeds with a normal amount of pedal force. The factory DOT3 fluid was toast. I didn't even install the pads and rotors.
My point is this car spent only 2 years in dry Los Angeles before the brake pedal went to crap. I think heat is the driver of fluid life. I think DOT4 would help here. Change your fluid folks.
The pads still looked meaty but I figured I'd change them out as well as the rotors. I ordered both.
Before doing the brake job, I wanted to flush the fluids and bleed. I bought the motiv hydraulic valve on amazon to assist in the one man bleed job (awesome tool). I flushed with generic DOT 3/4 fluid from RA. The brake performance is night and day. The car actually wants to stop at higher speeds with a normal amount of pedal force. The factory DOT3 fluid was toast. I didn't even install the pads and rotors.
My point is this car spent only 2 years in dry Los Angeles before the brake pedal went to crap. I think heat is the driver of fluid life. I think DOT4 would help here. Change your fluid folks.