Brake Fluid ????

[Chi Town Runner]

Is there a brake fluid that is compatible with lets say Dot-3 and Dot-4.

I just checked my brake fluid and it needs topping off.
It's '68 master cylinder with manual brakes 11" drums on the front.
When I rebuilt the car 10 + years ago and have since moved I don't remember what brake fluid I used and some of my stash of fluids are ?????
Any help ? I need to top off before the Hor Rod Tour tomorrow.

Thans anyone.

 

[Master Gunner]

The only brake fluid that is only compatible with itself is DOT 5, which is silicone. The main difference between DOT 3 and 4 4 is the boiling point, so go ahead and top off with 3 and you should be fine.

Mark

 

[Aron Gleason]

I would just stick with either Dot 3 or Dot 4 brake fluid.

 

[493 Mike]

The only brake fluid that is only compatible with itself is DOT 5, which is silicone. The main difference between DOT 3 and 4 4 is the boiling point, so go ahead and top off with 3 and you should be fine.

Mark

FYI>Read Rick Erenbergs answer to the fluid compatibility issue. They all must be compatible with the others or there would be huge legal liabilities for the manufacturers.

 

[RemCharger]

I guess you could literally mix n match transmission fluids as well.
And power steering fluids..
Coolants..

 

[Chi Town Runner]

OK

Thanks guy's for all your info and help.
It is deeply appreciated.

Frank

 

[Master Gunner]

FYI>Read Rick Erenbergs answer to the fluid compatibility issue. They all must be compatible with the others or there would be huge legal liabilities for the manufacturers.

DOT 5 is ONLY compatible with DOT 5!

Mark

 

[493 Mike]

I guess you could literally mix n match transmission fluids as well.
And power steering fluids..
Coolants..

Brakes are a safety item, the other stuff will only affect your wallet.
Mike

 

[MoparLeo]

https://centricparts.com/getmedia/a...nical_Whitepaper_D1-Brake-Fluid-1A_8-2018.pdf
The right answer is, if the fluid is 10 years old it needs to be flushed out. The boiling point degrades when moisture is absorbed using DOT 3 and 4 fluid.
DOT 4 starts out with better specs but degrades quicker than DOT 3 fluid over time.
All non synthetic brake fluid are "hygroscopic" meaning they absorb moisture, even through the rubber lines.
Brake fluid should always come from a new, sealed container. How expensive is a quart of high quality brake fluid ? Safety first.

 

[Photon440]

https://centricparts.com/getmedia/a...nical_Whitepaper_D1-Brake-Fluid-1A_8-2018.pdf
The right answer is, if the fluid is 10 years old it needs to be flushed out. The boiling point degrades when moisture is absorbed using DOT 3 and 4 fluid.
DOT 4 starts out with better specs but degrades quicker than DOT 3 fluid over time.
All non synthetic brake fluid are "hygroscopic" meaning they absorb moisture, even through the rubber lines.
Brake fluid should always come from a new, sealed container. How expensive is a quart of high quality brake fluid ? Safety first.

It's been a long time since I've seen any brake fluid that wasn't labelled "Synthetic". Anything you look at on the shelves - Prestone, Lucas, Castrol, Johnsens, Peak, Maxima, STP, they all say synthetic for type 3 and 4.

 

[RemCharger]

FYI>Read Rick Erenbergs answer to the fluid compatibility issue. They all must be compatible with the others or there would be huge legal liabilities for the manufacturers.

This is how they deal with huge legal liabilities