yamahaSHO

You only consider one person, who's mainly S2000 focused (nobody has heard of him elsewhere) the only credible person on brake fluid . If you really want a credible source, I'm sure my buddy Todd Cook would love to answer your questions on brakes. You can find him at www.tceperformanceproducts.com. He's been a friend for years and is who I direct my brake related questions to.

The manufacturer is very unlikely to recommend anything I use my car for... I've only been storing brake fluid for years and using it for high stress use (like my sig pic). I always have some on hand and although I always have a new bottle in the garage, I always finish one bottle before opening another. For reference, a metal can is much better for storage than plastic, which is why I say your 'in-use' fluid is more susceptible to absorbing moisture than the metal can something like Super Blue is shipped in. "Credible reference" - "The best type of container is a metal one, as it performs the function of a moisture barrier much better than thin plastic bottles - even when those plastic bottles are made from engineered materials. The technology does not exist today to make the plastic container perform as well as metal at a reasonable cost." - http://www.stoptech.com/technical-su...rs/brake-fluid






BITOG = www.bobistheoilguy.com

INDYMAC

You're a real gem Yamaha. Thanks.

jeffbrig

I agree, a metal can is superior to something plastic. However, when you open the metal can and use .8L of brake fluid, you've essentially replaced that fluid in the bottle with .8L of warm, moist air (I live in a brutally humid tropical climate). At that point, the bottle material is largely irrelevant. The .8L of very humid air is, at least in my mind, a LOT of moisture to be absorbed by the remaining .2L of brake fluid. So my preference is to discard the leftover fluid and use a fresh bottle when changing or bleeding fluid.

Obviously, a full (or nearly full) bottle keeps much better than a nearly empty one, as the air/fluid ratio in the bottle is much lower, so less moisture is introduced into the fluid while it sits there on the shelf.

yamahaSHO

Yes, you have a void of moist air, depending on your conditions, however, it won't easily absorb MORE through the container. It's no worse than when you pop the cap off the master cylinder reservoir.


Squeeze the can or bottle to mitigate how much air can actually be entrapped.

s2000Junky

Interesting question OP. Ive considered doing a similar thing, but rather use the dye as purely a marker, so I would not be contaminating the unused bottle of fluid going in to the car, but simply adding a few drops to the old in the master reservoir to gauge when the old is completely bled and the new uncolored fluid is in.

So add a few drops to the old fluid in reservoir, top of with fresh fluid when most the old colored is now in the lines, go to each caliper and bleed until clean fluid comes out.

Billman250

I have 30 years experience with brake fluid, many of those years were before s2ki or the S2000 existed.

SpitfireS

Well...
I would start a brake bleed with a cleaned and full reservoir, full with fresh fluid I mean.
The difference between old fluid and new, whatever color, is not that hard to see.
IMO it is important to have the smallest amount of old fluid in the caliper when you bleed it, IOW push/turn the piston all the way back in with the bleeder fully open (and full reservoir).
Do this slowly to avoid pushing old fluid back into the system, you want it out through the bleeder.
Then let gravity do its thing until the fresh fluid appears.
Sure, that is more work as you have to take the wheel off, remove at least 1 caliper bolt, remove pads, etc. but worth it as the main goal is to have fresh fluid in there.. right?

Maybe ATE would tell you what dye they used?

yamahaSHO

It appears my point was missed entirely...

jkelley

Thanks Billman for clearing this up. I never understood why this was such a big deal but as a gullible idiot I always tossed my half-used bottles after about a week if I didn't need to top anything off. There really shouldn't be any appreciable amount of water that could conceivably absorb into the contents of the bottle with a sealed lid...

I will save my partial bottles from now on

_brandon

The rule I have always used (not a mechanic) is if it has been opened and not used for 2-3 weeks then its considered garbage. Because brake fluid LOVES absorbing water. Like someone mentioned earlier, the moisture that is introduced into the bottle gets absorbed into the fluid. So for us living in humid climates (houston for instance) it is much more prevalent. Why risk such an important component over a few dollars? And back to OP's question.. Someone else hit the nail on the head by saying "why introduce water to the system with food dye?". Not to mention I dont think they will mix very well.. Could be wrong though. Just do it the way everyone else does. It should take more than a small bottle or two to complete the job.