brake fluid

[wolcott]

How long after you have opened up a bottle of Dot 4 brake fluid would you consider it still "good?" I was thinking 2 months maximum on a tightly-capped partially used bottle. Comments?

[DEF]

I buy small containers (12 oz, I believe)from the autoparts store and keep it tightly capped for the life of the container. I do not throw away a partially used container unless I have forgotten to close it after use...........these days, there is too much impact on the environment to discard such fluids. Just limit the exposure time to atmosphere and you'll be fine.

[Wooster]

For me, I'm thinking 2 hours but to each his/her own.

 

Wooster, frugel but willing to spend $2 for new bottle of DOT 4

[Ken H.]

I'm not sure what the recommended time to use after open is, but it's not very long. 2 hours is closer than 2 months IMHO.

[tonyla]

why does brake fluid go bad?

[wolcott]

from what I understand air/moisture will get into the container even if capped and contaminate the fluid. Brake fluid is hygroscopic (absorbing or attracting moisture from the air). I always thought it would be okay for 60 days, though. But, yes it is cheap enough not to worry about. Every 3 months in my home town, they have a hazardous item collection event where you bring anything that is considered hazardous to the collection point. That is where I bring everything except used motor oil which goes to the local Advance auto parts store.

[RFW]

How long after you have opened up a bottle of Dot 4 brake fluid would you consider it still "good?" I was thinking 2 months maximum on a tightly-capped partially used bottle. Comments?

Depends on a lot of things. How humid was it when you opened it? How humid is it when it was in storage? How good is the seal?

 

If the bottle was opened and partially used in a relatively dry environment, and care was taken not to damage the seating surface where the cap screws down on, and it was screwed on tight, then the stuff will last a LONG time. Well over a year. Probably way more.

 

If all the above precautions were observed, then there are only 2 ways to get moisture into the fluid. One is the moist air that entered as you poured some fluid out. But that is potentially only a tiny amount.

 

The second is via permiability of the plastic container itself, but that is a constant process that will occur whether you open it or not.

 

The "use it up immediately and don't store it" warnings are there to cover all possible situations, including the average Joe being sloppy about resealing it.

 

Besides, you have to ask why is it, if the fluid is considered safe for a year or two, when installed in the bike and exposed to rain and humidity, that a properly recapped bottle of the stuff, sealed better than it is in the bike's hydraulic system and stored indoors is only good for a couple of months?

 

Makes no logical sense!

 

Bob.

[RFW]

For me, I'm thinking 2 hours but to each his/her own.

 

Wooster, frugel but willing to spend $2 for new bottle of DOT 4

Two HOURS???? You're joking, right? It it really is THAT hygroscopic (it's nowhere near!), then the fluid in the bike ought to be changed out every day!

 

Bob.

[DEF]

For me, I'm thinking 2 hours but to each his/her own.

 

Wooster, frugel but willing to spend $2 for new bottle of DOT 4

Two HOURS???? You're joking, right? It it really is THAT hygroscopic (it's nowhere near!), then the fluid in the bike ought to be changed out every day!

 

Bob.

 

Bob, you're correct....but, the DOT4 should be changed every time you put the brakes on.....heh-heh!

 

OK, now look folks, the DOT4 you bought already has some water in it. The product is tested by one of two methods;

 

1-LOD (loss on drying).

2-KF moisture analysis (A titration that is speciic for water).

 

Request a MSDS for the product and see what the spec is for water.....you might be surprised.

 

As your can of DOT4 makes its way to you, it does NOT pick up more water. The only time it can absorb water is when the can is open, exposed to more water than is already in the can (water has a vapor pressure).

 

If you want to dry our your brake fluid, put the can in the oven at 200 F. for an hour (remove the cover so the water can escape). Otherwise, quit worrying about your damn brake fluid (2 weeks? ridiculous. 2 days? find another hobby...motorcycles are not for you).

[Wooster]

For me, I'm thinking 2 hours but to each his/her own.

It's a pun ! Well, hyperbole, analogous to exaggeration.

 

Is brake fluid bottle good two days, weeks, months or years ? I don't know, so I "use only DOT 4 brake fluid from sealed container" (hmmm, where's that quote from).

 

Wooster w/o fluid problems

 

Boiled egg in morning is hard to beat

[Firefight911]

Small point of order for those so wrapped up in whether there is brake fluid in their water.

 

When placing said bottle of brake fluid in oven; one should inspect their bottle to ensure it is of the composition other than plastic! Last time I checked, plastic, when placed near the vicinity of water in brake fluid, has a high tendency to melt and/or catch fire when subjected to temperatures above those of ambient atmospheric air.

 

And remember, once you have completed "drying" your fluid, you will need to set it out on a cooling rack to reduce its temperature to the point of being able to touch bottle.

 

Again, leave lid off!!! This does two things. It allows all previously dried moisture to re enter bottle/fluid and prevents bottle from forming vacuum on inside from cooling effect.

 

Final step. Repeat above procedure due to cooling process allowing all fluid/moisture to return to previous state.

 

[Wooster]

Small point of order for those so wrapped up in whether there is brake fluid in their water.

 

When placing said bottle of brake fluid in oven; one should inspect their bottle to ensure it is of the composition other than plastic! Last time I checked, plastic, when placed near the vicinity of water in brake fluid, has a high tendency to melt and/or catch fire when subjected to temperatures above those of ambient atmospheric air.

 

And remember, once you have completed "drying" your fluid, you will need to set it out on a cooling rack to reduce its temperature to the point of being able to touch bottle.

 

Again, leave lid off!!! This does two things. It allows all previously dried moisture to re enter bottle/fluid and prevents bottle from forming vacuum on inside from cooling effect.

 

Final step. Repeat above procedure due to cooling process allowing all fluid/moisture to return to previous state.

 

 

And this saves two bucks (price of 12 oz DOT 4 @ Wally World). Spend $2; save oven for baking brownies.

 

Wooster

 

On one hand, I question utility of baking brake fluid, on other hand, I wear a glove

[ShovelStrokeEd]

On the gripping hand, baking the stuff in open air is likely to make it more hygroscopic than it already is as well as possibly decomposing some of the other stuff in there. Methinks it's a bad idea. Not sure the spousal unit would approve of something in her oven giving off noxious fumes not to mention the sudden removal of all humidity from the room is liable to kill house plants and small pets.

 

Spend the coupla bucks and buy a new, sealed container for each and every brake service. Sheesh! BTW, it is doubtful that your dealer is taking anywhere near the precautions mentioned. Whatllya bet there is a communal container back in the service area?