Opened brake fluid: problems OTHER THAN lower boiling point?

[d00df00d]

I know opened brake fluid is subject to moisture lowering the boiling point. Are there any other risks associated with it?

I always have some amount of opened but unused Castrol SRF kicking around. SRF's wet boiling point is over 500º F, which is higher than the dry boiling point of many DOT4 (let alone DOT3) fluids.

Our Mazda5 only calls for DOT3.

...Y'all see where I'm going with this?

 

[ctechbob]

Corrosion in the system caused by the moisture.

 

[Vercingetorix]

Brake fluid is how much?

 

[Leo99]

Brake fluid is hygroscopic. Meaning it absorbs water from the atmosphere. Moisture in brake lines could cause corrosion as Ctechbob said above. It's cheap stuff. Buy fresh if there is a concern.

 

[KGMtech]

It's so inexpensive and your time is worth so much more..just get fresh stuff and call it a day.

 

[97prizm]

I know opened brake fluid is subject to moisture lowering the boiling point. Are there any other risks associated with it?

I always have some amount of opened but unused Castrol SRF kicking around. SRF's wet boiling point is over 500º F, which is higher than the dry boiling point of many DOT4 (let alone DOT3) fluids.

Our Mazda5 only calls for DOT3.

...Y'all see where I'm going with this?

From what I understand with my Mazda Racecar, DOT fluid is backwards not necessarily forwards compatible. I'm not a chemist but I switched to ATE superblue brake fluid and noticed a slightly spongier feel. It could have been the age of the components.

 

[edyvw]

I know opened brake fluid is subject to moisture lowering the boiling point. Are there any other risks associated with it?

I always have some amount of opened but unused Castrol SRF kicking around. SRF's wet boiling point is over 500º F, which is higher than the dry boiling point of many DOT4 (let alone DOT3) fluids.

Our Mazda5 only calls for DOT3.

...Y'all see where I'm going with this?

NO, NO AND NO!!!

SRF is hydrophobic fluid. Basically it isolates moisture. Wet boiling point is measured at 3.49%. So, that fluid being open might have it more. But bigger issue is that once in system, and mixed, with moisture that is now isolated, and moisture already in old fluid, it will again isolate moisture which will create wet pocket.
Using fresh SRF is also sometimes problematic if system is not thoroughly flushed. If there is old fluid left, again, SRF will isolate it and wet pocket will be present.
IMO, using STF, at BARE minimum, 2ltrs of fresh stuff to flush old fluid properly, using also computer to flush out ABS module.

 

[slacktide_bitog]

Some Corvettes have had problems after using SRF since it seems to react with the magnesium used in some components

Bosch ESI6 is a good price for a great brake fluid, but even the cheapest DOT 3 or 4 on sale is perfectly fine to use

 

[Yuk]

How long can one use brake fluid after a the jug has been opened? What if it is capped immediately after opening?

 

[d00df00d]

Corrosion in the system caused by the moisture.

Nice. Thanks.

SRF is hydrophobic fluid. Basically it isolates moisture. Wet boiling point is measured at 3.49%. So, that fluid being open might have it more. But bigger issue is that once in system, and mixed, with moisture that is now isolated, and moisture already in old fluid, it will again isolate moisture which will create wet pocket.
Using fresh SRF is also sometimes problematic if system is not thoroughly flushed. If there is old fluid left, again, SRF will isolate it and wet pocket will be present.
IMO, using STF, at BARE minimum, 2ltrs of fresh stuff to flush old fluid properly, using also computer to flush out ABS module.

Where did you read this? It reads a lot like the warnings against DOT5 brake fluids, which SRF isn't.

Castrol says SRF "absorbs less water than conventional glycol ether fluids," not that it's hydrophobic.

https://www.castrol.com/en_us/united-states/home/motorcycle-oil-and-fluids/brake-fluids.html#tab_castrol-react-srf-racing-brake-fluid

 

[hrv]

Brake fluid is how much?

YUP.. Just get a new bottle..

 

[Nukeman7]

Brake fluid is how much?

It's so inexpensive and your time is worth so much more..just get fresh stuff and call it a day.

YUP.. Just get a new bottle..

Looks like the Castrol SRF brake fluid is ~$80 per liter!

 

[Faawrenchbndr]

Toss it on the recycle oil bucket……buy new fluid

 

[KrisZ]

Depends on what you man by "open". Is it open, as in the bottle is without a cap? Or is it open, as in it was used before and then the cap put on tight?
Definite NO to the former and maybe to the latter depending how long it sat and in what conditions.

 

[Kira]

SRF? ...Synthetic Racing Fluid?

 

[edyvw]

Nice. Thanks.


Where did you read this? It reads a lot like the warnings against DOT5 brake fluids, which SRF isn't.

Castrol says SRF "absorbs less water than conventional glycol ether fluids," not that it's hydrophobic.

https://www.castrol.com/en_us/united-states/home/motorcycle-oil-and-fluids/brake-fluids.html#tab_castrol-react-srf-racing-brake-fluid

Your call. It is exceptional stuff, but thorough flush is needed. I know some people who use it on track bcs. it allows them to run one season without change, but I know there were issues with it bcs. people didn’t want to flush al the way as it is expensive.

 

[d00df00d]

Depends on what you man by "open". Is it open, as in the bottle is without a cap? Or is it open, as in it was used before and then the cap put on tight?
Definite NO to the former and maybe to the latter depending how long it sat and in what conditions.

The latter.

 

[Marcozi]

Toss it on the recycle oil bucket……buy new fluid

Properly dispose of the brake fluid at your town/city/county waste disposal facility. Brake fluid is highly corrosive.

 

[Faawrenchbndr]

Properly dispose of the brake fluid at your town/city/county waste disposal facility. Brake fluid is highly corrosive.

Well yes……. did you miss the “recycle oil bucket”?

 

[PF52]

Properly dispose of the brake fluid at your town/city/county waste disposal facility. Brake fluid is highly corrosive.

Or just put the old fluid back in the bottle, clean it up real nice and take it back to Walmart for a refund. Which is what some guy did before me and I am the lucky one who bought it!