Reason to use DOT 3 brake fluid instead of DOT 4?

[GiveMeAVowel]

Originally Posted By: labman

Originally posted by S2000driver:
[QB] FYI-

Here's more info about the Honda fluid, if you care.

Why must I use Genuine Honda DOT 3 brake fluid?

Genuine Honda DOT 3 brake fluid is formulated to minimize water absorption under all conditions.


When tested in a mass spectrometer, Honda Brake Fluid had dramatically less dissolved copper material than the leading competitors, clear proof of superior corrosion protection.

Copper?

Does Honda use copper or brass brake components? I have seen old master cylinders that were sleeved in brass, but I assumed they were retrofits. Sure a big surprise when you run a hone through them.


VERY IMPORTANT ALTHOUGH YOU DO NOT HAVE TO USE HONDA BRANDED
DOT 3, AS ANY DOT 3 WILL PROVIDE THE SAME PROTECTION
AS OPPOSED TO NEWER DOT 4 WHICH HAS CERTAIN HARSHER INGREDIENTS THAT DO NOT WORK WELL WITH OLDER HONDA VEHICLES!!!!!

I BELIEVE SOMEONE ELSE BROUGHT UP THAT DOT 4 MAY CONTAIN SOME MORE CAUSTIC ADDITIVES THAT WHILE SAFE FOR NEWER MODELS CAN CAUSE EARLIER FAILURE RATES ON OLDER MODELS THAT WERE SPECIFICALLY DEVELOPED FOR
DOT 3 ONLY.

 

[Yah-Tah-Hey]

.Largel aircraft use a phosphate ester base brake fluid that won't burst into flames if it contacts white hot brake assemblies. Generating stations use a phosphate ester base hydraulic fluid to actuate turbine control and stop vales that operate near 1000F. Systems using these fluids require special seal and o-ring and gasket material. Maintenance personnel should be trained before being allowed to work on equipment using ester based fluids. Pay me now or pay me later.

 

[Tones]

The arguments I have heard are that DOT4 absorbs water faster, but wet boiling point for most DOT4s are still on par with dry boiling point of DOT3s, so in that way it is not a safety issue but a corrosion/reliability issue. If you plan to change on some regular interval then DOT4 will work. If not stick to DOT3.

 

[andyd]

I use the Valvoline because it is cheap and available.

 

[MolaKule]

Quote:
I BELIEVE SOMEONE ELSE BROUGHT UP THAT DOT 4 MAY CONTAIN SOME MORE CAUSTIC ADDITIVES THAT WHILE SAFE FOR NEWER MODELS CAN CAUSE EARLIER FAILURE RATES ON OLDER MODELS THAT WERE SPECIFICALLY DEVELOPED FOR
DOT 3 ONLY.



Pleaeeaase turn your caps off.

Secondly, I do not think that is a correct statement.


Brake Fluid Chemistry

 

[GiveMeAVowel]

What about this factor Mola?
Quote:

Dot 4 brake fluids contain borate esters to increase the boiling point. However, borate esters can cause rubbers seals made of SBR (styrene-butadiene rubber) in the master cylinder to swell. This can cause tears in the rubber as the piston moves back and forth.

 

[MolaKule]

Originally Posted By: GiveMeAVowel



What about this factor Mola?
Quote:

Dot 4 brake fluids contain borate esters to increase the boiling point. However, borate esters can cause rubbers seals made of SBR (styrene-butadiene rubber) in the master cylinder to swell. This can cause tears in the rubber as the piston moves back and forth.


That's why styrene-butadiene elastomers are not used in most master cylinders.

This was the primary reason for the recall of certain brake systems in some Asian vehicles a few years back.

 

[GiveMeAVowel]

Originally Posted By: MolaKule


That's why styrene-butadiene elastomers are not used in most master cylinders.

This was the primary reason for the recall of certain brake systems in some Asian vehicles a few years back.


What about much older asian vehicles like my old 94 Accord? How would I be able to know which type of seal material is used, should I be concerned? It would see like older asian vehicles made before DOT4 became widely used OEM, might have those types of seals.

 

[MolaKule]

I don't think you have to worry.

I will try and find those article links.

 

[stchman]

Only cost.

If DOT 3 and DOT 4 are the same price, use DOT 4.

Use DOT 4 if the vehicle's manufacturer calls for DOT 4.

Think of DOT 4 as a higher temperature version of DOT 3.

Please do not confuse DOT 5 with DOT 5.1!!1 DOT 5.1 is an even higher temperature version than DOT 4.

 

[MolaKule]

Originally Posted By: stchman
Only cost.

If DOT 3 and DOT 4 are the same price, use DOT 4.

Use DOT 4 if the vehicle's manufacturer calls for DOT 4.

Think of DOT 4 as a higher temperature version of DOT 3.

Please do not confuse DOT 5 with DOT 5.1!!1 DOT 5.1 is an even higher temperature version than DOT 4.

Dot 5 is not to be used in a system calling for DOT 3, DOT 4, or DOT 5.1.

DOT 5 is a silicon based fluid NOT compatible with DOT 3, DOT 4, or DOT 5.1 brake systems.