Are all DOT 4 brake fluids the same?

[Duporth]

I am planning to do the brake fluid flush (and clutch) on my ST1300, so I need 3 bottles of DOT 4 fluid.

A question comes to mind; are all DOT 4 brake fluids the same, or like engine oils, are there some secret and beneficial additives in some brands of brake fluid?

Thank you, D

 

[Andrew Shadow]

My limited knowledge has taught me that there are minor differences between manufacturers. The most significant one that I am aware of is with the rated boiling points, which, in the case of the wet boiling point in particular, is a reflection of the fluids ability to deal with absorbed moisture.

Any brake fluid meeting the DOT 4 specification will be suitable in any vehicle that requires DOT 4 brake fluid, assuming that it is being driven under the conditions that the vehicle manufacturer intended. i.e. public road use as opposed to being used as a race track motorcycle.
This also assumes that the fluid will be flushed at the intervals intended by the manufacturer.

In my opinion, more so than a particular brand, it is important to buy brake fluid from an established and reputable brand as opposed to a no-name/unknown brand fluid such as is often found in convenience stores- I have no desire to use brake fluid labeled as Top Dog Dot 4 Brake Fluid that comes from parts unknown. Hopefully this increases the odds that the fluid that is in the container is actually what the container states that it is, and that it actually does meet all DOT 4 standards needed to be labeled as such. Which one of those particular brands is of less importance to me.

 

[Capital]

DOT4 specification is restrictive enough, so that manufacturers don’t have much area to improvise (as opposed to oil).
Make sure it is a reputable brand - as Andrew stated above, I also try to avoid generic/random brands. Better visit a bigger automotive shop, where DOT4 is sold on a daily basis and doesn’t sit on shelf for long. Then buy a brand you can recognize.

 

[nicksacco]

There is a specific sequence for changing fluid in the brakes.
Let us know if you already have that info or if you need it.

 

[ReSTored]

I buy Prestone in the 12oz size and change out fluid every 2 years. I buy at Walmart where turnover is good, as is the price.

Prestone® DOT 4 Brake Fluid - Prestone® Total Protection

Prestone® DOT 4 Motor Vehicle Brake Fluid delivers enhanced performance vs. DOT standards, benefitting all vehicles calling for DOT 4. This synthetic fluid starts with a higher dry boiling point than the DOT minimum standard to protect against overheating, brake fade and performance decline due...

prestone.com

 

[snowmoer]

I use Prestone also. Been using it for as long as I can remember in all my vehicles. I have never had any brake problems. Changing it every few years is the important part.

 

[SMSW]

or like engine oils, are there some secret and beneficial additives in some brands of brake fluid?

What secret and beneficial additives do you have in mind? CBD oil?

 

[mello dude]

If you google...LelandWest brake fluid chart, .....some interesting stuff..

 

[Al st1100]

just when you thought " all the same " if it has a dot 4 rating.. Look at the different boiling points, big difference https://thebuildjournal.com/tech-guides/ultimate-brake-fluid-comparison-guide/

 

[Duporth]

Thank you everyone for your helpful replies. The LelandWest site is interesting (thanks mello d) and it is clear there are many different recipes used by manufacturers.
I can buy Castrol in a few different DOT4 specs locally, so off I go
D

 

[ST1100Y]

I'd focus on MFG date and shelf life...
I also use an already unsealed container (regardless of it's screw cap) only for flushing, the final fill always comes from a fleshly opened bottle...

 

[SMSW]

just when you thought " all the same " if it has a dot 4 rating.. Look at the different boiling points, big difference https://thebuildjournal.com/tech-guides/ultimate-brake-fluid-comparison-guide/

If you look at the DOT 4 fluids only, the differences are not that great*. A better metric would be to check the specs for DOT 4 and see if the brand of your choice falls within those parameters. That is all you need, unless you are going racing. If your brake fluid never goes over the boiling point of water, does brake fluid with a dry bp of 500º +/- 15º matter? A better question is, how old is the fluid in your system?

*I think there were one or two outliers.

 

[Al st1100]

If you look at the DOT 4 fluids only, the differences are not that great*. A better metric would be to check the specs for DOT 4 and see if the brand of your choice falls within those parameters. That is all you need, unless you are going racing. If your brake fluid never goes over the boiling point of water, does brake fluid with a dry bp of 500º +/- 15º matter? A better question is, how old is the fluid in your system?

*I think there were one or two outliers.

To me it looks like the standard is pretty loose but the prices of the "same stuff" is wide ranging. I'll have to check what kind of fluid my Bugatti uses

 

[MichaelB]

I typically use Prestone DOT 4. I use it because it is a water clear fluid. Others I have used seem to have a yellowish tinge to them.

 

[rogo]

Real marketing on the shelves. Beware.

 

[dduelin]

I pretty much stick to Valvolene and Prestone brands. It’s more important to do the flush and bleed on time and completely rather than obsessing over brand.