Open Brake Fluid Can-Problem? Need Advice
 

Back in October, I needed to open a can of ATE for a smidgen of fluid-no more than 3 or 4 oz. The can was opened new, poured what I needed, and immediately re-closed with the stock cap.

My question is-how bad this fluid may be with regard to moisture saturation? I need to flush/bleed this weekend for my DE next weekend, and I'd really like to use this fluid up, it's such a waste. Having said that, I don't want to have a spongy pedal the first day.

Any experiences out there? BTW, I'm also installing my new Speed Bleeders this weekend.

It might be OK. ATE used to be a 180 day fluid back in DC. Other brands were 90 days. If it were me I would flush the whole system. Its been a wet winter here in TX. Then again, the cooler temps would be easier on the braking system. Are you going to MSR next week?

I would not use it, personally, on a tracked car. $12 or whatever is not much for track peace of mind. IMHO of course. If you have a daily driver or wife's car or something you could use it to refill, although the blue will stain the typical LDPE reservoirs.

Thanks guys. I actually goofed by posting in the engine forum. I've got a brand new can of ATE, but I've been looking at this "old" one longingly...I'll toss it.

Jamie: I will be at MSR next weekend-#63.

If you changed your brake fluid since October,the stuff in the can is better than whats in the car.

I sent an apprentice to go and buy a tin of brake fluid from the local store.
He came back shaking it like you would shake a carton of orange.

Do they teach them NOTHING in college these days????

If it were pricey BF (you be the judge of that), you could load up the partially empty can with ball bearings or marbles to displace the air. Might help some. As ficke mentions, what's left in the can is probably slightly better than what's in the brake system.

Sherwood

Help me understand something guys... If I've got a a partial can of fluid remaining from my last flush/refill (say it's been opened for six months or so), how can the fluid in the can be any worse (from exposure to air) than the fluid in the car? I've never understood the logic behind only using unopened fluid (for topping off/bleeding). Opinions???

The thought is that once the can is opened humidity has been introduced to the fluid. When you close the can and seal the moist air in the can with the fluid it will absord the moisture into the fluid.

I agree whats in the can has to be a LOT better than what is in the car.

Suggestion, use it. Then bring a fresh can and bleed at the track again. Unless you dont want to think about the possibility of brake fade while driving.

Is brake fluid really that sensitive to moisture? Say you open a new quart can on a very humid day, use half, then seal the can. The air in that can will have <0.01 grams of water in it. If the remaining brake fluid absorbs all of that water, that's <0.002% by weight. Will that minute amount significantly reduce the boiling point?

Too late! I opened a new can of ATE and flushed-I'll use the rest of the can to bleed at the track.

For future reference, what if one were to blow nitrogen or something into a partially used can to displace the air prior to capping?

You could... they sell stuff like that for wine...

I really don't see the need to flush fluid after every track day. Somebody tell me why the fluid won't be good for at least a few months!

The same goes for the fluid in the can.

All you have to do is examine the time curves for wet/dry boiling pt.s and the answer should be obvious.

I think the long-used advise is for regular car owners who will tend to leave a previously opened can on the garage shelf for years before topping off. That, plus the fact people don't ever flush the system and they buy the cheapest BF they can find at Pep Boys (or equivalent), the stuff that meets only minimum DOT specs. If you're going to flush, bleed and refill on a regular basis, I wouldn't worry about it.

The reason so many folks resort to the scheduled system bleed is because the fluid has air in it from overheating (boiling). Maybe it's better to resort to other methods to prevent this in the first place (e.g. better fluid, more air to rotor, etc.).

FWIW, I notice a lot of people use ATE BF. However, according to specs, their wet boiling rating is 40º lower than the comparably priced Motul RBF.

Sherwood
http://www.seinesystems.com/BrakeFluids.htm
no affiliation

I agree there is no need to flush the entire system after each track day. I would, however bleed the brakes again after the track day is over.

I'm curious how most dispose of used BF. Batteries and motor oil are one thing but never heard what to do with BF.

Toss it. I've fond that fluid is a moisture whore and $10 isn't worth your life -

Craig

ATE 1/2 the price of the RBF from my source. Well, it's the same price for 1/2 the quantity, and I tend to flush a whole can of ATE just for good measure... maybe I need to be more efficient. That said, I'm planning to try the motul RBF 600 next.

can you point me to these curves? I would think they would be based on ambient humidity and surface area of fluid exposed to the atmosphere. I am motivated to change because getting some soft pedal in a track weekend is normal for me with brand spanking new ATE Blue.

Motul:
EXTREME THERMAL RESISTANCE AND STABILITY: the elevated boiling point of RBF 600 FACTORY LINE (312°c / 594°F) enables effective braking even under the extreme conditions of competition.

VERY EFFICIENT WHEN 'WET': the very high wet boiling point (216°c / 421°F), is superior to conventional brake fluids & provides a particularly efficient braking system in rain and helps stave off vapor lock, ie boiling fluid.
-----------------------------------------------------------
ATE:
Boiling point:
at least 280°C

Wet boiling point:
at least 200°C
-----------------------------------------------------------

Motul is a better fluid.

"tend to leave a previously opened can on the garage shelf for years"
- definitely agree

Rick - re disposal - brake fluid is hazardous waste and must be disposed of as such. A shop or retailer might take it, or take it to your haz. waste facility. I do the latter here. Your city might have a law that the 2st two places may have to accept used brake fluid.

It is nasty stuff - besides the above it will take the paint right off your car...

I discussed this issue with Valvoline.
 

It's been a couple years now but I've attached the link to the discussion on brake fluid shelf life that I posted. You will be ok since the fluid is less than 6 months old and it was closed tightly.

http://forums.pelicanparts.com/showthread.php?s=&threadid=99744&perpage=20&highli ght=shelf&pagenumber=1