Questions about mineral brake fluid.

[LonesomeSTX]

I have some mineral brake fluid left over from a truck I had that had wet brakes. What would happen if I used this fluid on my conventional brake systems? Could it be mixed with the DOT or silicone stuff I have? What makes it different from other brake fluids? If I cannot use it with what I have, what else is it good for?

 

[kryptonitecb]

I don't know if you can use it in a DOT system however it is best to never mix different brake fluids. Some can be mixed with higher or lower numbers, some can't, some brake systems can use dot 4 or 5 but not 3 etc. The safe answer is always use the recommended fluid for the master cylinder and calipers. I ran into a similar issue when changing MC on a motorcycle and had to drain & flush the system cause I mixed dot5 with the old dot3.

Also if mineral oil is anything like brake fluid it will absorb moisture over time and become "bad".

Sent from the road while ignoring traffic

 

[LonesomeSTX]

I get that. I wonder if it will owrk with my bike or ATVs.

 

[exbass94]

I have never heard of "mineral" brake fluid before. DOT 3, DOT 4 and DOT 5.1 are made from polyglycol ether, which is alcohol based. DOT 5 is silicone based. Systems designed for polyglycol fluids are absolutely NOT compatible with petroleum products. Petroleum will make the rubber hoses and seals swell and break apart. So no, I would defintely not use it any brake system not specifically designed for it.

 

[LonesomeSTX]

That makes sense to me.

 

[armadillon]

If I was stranded and needed fluid immediately I might mix, but brake fluid is cheap enough that you shouldn't ever have to mix it.

 

[Snoranger]

I have never heard of "mineral" brake fluid before. DOT 3, DOT 4 and DOT 5.1 are made from polyglycol ether, which is alcohol based. DOT 5 is silicone based. Systems designed for polyglycol fluids are absolutely NOT compatible with petroleum products. Petroleum will make the rubber hoses and seals swell and break apart. So no, I would defintely not use it any brake system not specifically designed for it.

Mineral oil is used in bicycles with hydraulic brakes. I dont know of anywhere else.


No, dont mix it. How old is the fluid? If its a few years old, throw it away. (that goes for pretty much any brake fluid.)

 

[LonesomeSTX]

I am not sure how old it is.