I was just wondering if different brands of break fluid or DOT 4 compared to DOT 3 fluids really make a difference in pedal feel or break performance? I normaly use what ever DOT 3 spec break fluid that is on sale and I have never really noticed anything different from the factory original fluid in reguards to pedal feel or breaking performance. Am I missing anything?
Do break fluids really make a difference?
- Thread starter CharBaby
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What's break fluid?
OHHHHH! Im sorry Brett. LOL!(Brake Fluid). My spelling is terrable and I don't use spell check unless it's for important things like resumes' or letters to congress.
Keep in mind that DOT 3 and DOT 4 are not compatible and you would need to do a complete flush to get the old DOT 3 out of there. DOT 4 is supposed to be repellent to water which causes any moisture to stay separated from the fluid which can cause corrosion issues if that water is actually in a wheel cylinder or in the wrong areas of the master cylinder. I'd stick with the DOT 3. Some brands do perform better than others with higher dry and wet boiling points. I suppose it depends on what is on sale but if you are a casual driver and you don't brake hard frequently and don't race or stop from very high speeds on the highway or descend hills then you will probably be fine with whatever is on sale.
3 and 4 are fully compatible. It is 5 made from silicone that is not compatible. It must be fully flushed or there will be problems.
Richard.
Richard.
there is also dot 5.1. and dot 4 is said to be more absorbent of ambient water than dot 3.
ignore the more absorbent part. when are we getting an edit post feature?
Kestas
Staff member
Kestas
Staff member
CB, DOT 3 or DOT 4 are both fine for your application. DOT 3 is cheaper. DOT 4 is for people who drive their cars hard or do a lot of braking coming down a mountain, especially in desert climates... or for cars that are designed to use DOT 4.
I don't see where DOT 4 is for extreme applications. I see many fluids that are 3 and 4 rated and are only a couple bucks for a 12 oz can.
Kestas
Staff member
In general, DOT 4 has a higher wet and dry boiling point than DOT 3. That makes it applicable for extreme application.
Anything that is DOT 4 will meet DOT 3 requirements. That's why you see DOT 4 product labeled that it may be used where DOT 4 or DOT 3 are required.
Maybe this will help:
Brake Fluid
ARRANGED BY DRY BOILING POINT:
DRY:401F -- WET:284F --- DOT3 MINIMUM
DRY:446F -- WET:311F --- DOT4 MINIMUM
DRY:500F -- WET:356F --- DOT5.1 MINIMUM
DRY:502F -- WET:343F --- VALVOLINE SYNPOWER
DRY:509F -- WET:365F --- MOTUL 5.1
DRY:527F -- WET:302F --- AP RACING 551
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200
DRY:590F -- WET:410F --- AP RACING 600
DRY:590F -- WET:518F --- CASTROL SRF
DRY:593F -- WET:420F --- MOTUL RBF600
DRY:610F -- WET:421F --- NEO-SYNTHETIC SUPER DOT 610
DRY:620F -- WET:425F --- COBALT SUPER XRF
ARRANGED BY WET BOILING POINT:
DRY:401F -- WET:284F --- DOT3 MINIMUM
DRY:527F -- WET:302F --- AP RACING 551
DRY:446F -- WET:311F --- DOT4 MINIMUM
DRY:502F -- WET:343F --- VALVOLINE SYNPOWER
DRY:500F -- WET:356F --- DOT5 MINIMUM
DRY:509F -- WET:365F --- MOTUL 5.1
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200
DRY:590F -- WET:410F --- AP RACING 600
DRY:593F -- WET:420F --- MOTUL RBF600
DRY:610F -- WET:421F --- NEO-SYNTHETIC SUPER DOT 610
DRY:620F -- WET:425F --- COBALT SUPER XRF
DRY:590F -- WET:518F --- CASTROL SRF
Anything that is DOT 4 will meet DOT 3 requirements. That's why you see DOT 4 product labeled that it may be used where DOT 4 or DOT 3 are required.
Maybe this will help:
Brake Fluid
ARRANGED BY DRY BOILING POINT:
DRY:401F -- WET:284F --- DOT3 MINIMUM
DRY:446F -- WET:311F --- DOT4 MINIMUM
DRY:500F -- WET:356F --- DOT5.1 MINIMUM
DRY:502F -- WET:343F --- VALVOLINE SYNPOWER
DRY:509F -- WET:365F --- MOTUL 5.1
DRY:527F -- WET:302F --- AP RACING 551
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200
DRY:590F -- WET:410F --- AP RACING 600
DRY:590F -- WET:518F --- CASTROL SRF
DRY:593F -- WET:420F --- MOTUL RBF600
DRY:610F -- WET:421F --- NEO-SYNTHETIC SUPER DOT 610
DRY:620F -- WET:425F --- COBALT SUPER XRF
ARRANGED BY WET BOILING POINT:
DRY:401F -- WET:284F --- DOT3 MINIMUM
DRY:527F -- WET:302F --- AP RACING 551
DRY:446F -- WET:311F --- DOT4 MINIMUM
DRY:502F -- WET:343F --- VALVOLINE SYNPOWER
DRY:500F -- WET:356F --- DOT5 MINIMUM
DRY:509F -- WET:365F --- MOTUL 5.1
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200
DRY:590F -- WET:410F --- AP RACING 600
DRY:593F -- WET:420F --- MOTUL RBF600
DRY:610F -- WET:421F --- NEO-SYNTHETIC SUPER DOT 610
DRY:620F -- WET:425F --- COBALT SUPER XRF
DRY:590F -- WET:518F --- CASTROL SRF
In general, you should change DOT 4 brake fluid every 2 years and DOT 3 brake fluid every 3 years, because DOT 4 fluid assorbs moisture more readily than DOT 3 fluid.
For most daily drive cars, DOT 3 fluid is all you need, except where it is recommended to use DOT 4.
For most daily drive cars, DOT 3 fluid is all you need, except where it is recommended to use DOT 4.
Applicable? OK, but not exclusive to extreme applications. What will I save by buying a DOT 3 only? a quarter? fifty cents? what is the point?
For the guy that rarely/never changes his fluid, even if DOT4 BP drops more rapidly, the wet boiling point is higher, so wouldn't he be better off with a DOT4 in there?
Kestas
Staff member
Where I shop, the price for DOT 4 is 50% more than DOT 3. Why should I buy more performance than I need? It's almost like buying 93 octane for my 87 octane engine. I don't use synthetic motor oil, nor synthetic transmission fluid. Nor do I sport with my car. So why should I pay a premium and use DOT 4 for my DOT 3 vehicles in the frigid climate of flatland Michigan? I don't see the point.
For that matter, why aren't you using DOT 5.1? It's easily available where I shop, and far superior to DOT 4.
For that matter, why aren't you using DOT 5.1? It's easily available where I shop, and far superior to DOT 4.
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At the Carley automotive library;
http://www.aa1car.com/library/bfluid.htm
the above article says:
"DOT 4 fluid, which has a higher minimum boiling temperature requirement (446 degrees F dry and 311 degrees wet) soaks up moisture at a slower rate but suffers an even sharper drop in boiling temperature as moisture accumulates. Three percent water will lower it's boiling point as much as 50%!"
This is compared to DOT 3.
A good read - look at it, but I don't vouch for it's accuracy.
http://www.aa1car.com/library/bfluid.htm
the above article says:
"DOT 4 fluid, which has a higher minimum boiling temperature requirement (446 degrees F dry and 311 degrees wet) soaks up moisture at a slower rate but suffers an even sharper drop in boiling temperature as moisture accumulates. Three percent water will lower it's boiling point as much as 50%!"
This is compared to DOT 3.
A good read - look at it, but I don't vouch for it's accuracy.
Great replies from all, Thanks!
Note that DOT 3 won't meet the specs required for a Volvo. You will have to use DOT 4+/SuperDOT4/DOT 5.1 for that extreme application.
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