GenVibe - Community for Pontiac Vibe Enthusiasts

...so I have a partial bottle of brake fluid almost a year old that's been capped on the shelf, is it too old to use? I'd like to refresh my fluid and bleed my brakes.

I believe brake fluid goes bad because it absorbs water. If the container was sealed, it should be fine to use. I would use it. I've never had a brake system failure from moisture in the fluid.

Tightening the cap isn't really sufficient to lock out water. New brake fluid shouldn't cost so much that it's worth risking it.

It's very hygroscopic. You'll need a full bottle anyways to do a full flush. Buy a new one.
If you can find the colored stuff, it makes doing a flush easy. When the colored stuff appears you know it's fresh right through the system.

...well its a large size bottle that's almost full and should be enough to do the brakes....I don't see it being any different than the master cylinder screw on lid?

dnoishere wrote:...well its a large size bottle that's almost full and should be enough to do the brakes....I don't see it being any different than the master cylinder screw on lid?

Actually, the master cylinder is vented!

Chiadog wrote:

dnoishere wrote:...well its a large size bottle that's almost full and should be enough to do the brakes....I don't see it being any different than the master cylinder screw on lid?

Actually, the master cylinder is vented!

And only one way. Stuff goes out, not in.

I would not worry about failure it should be fine to use. Though like it has been mentioned, brake fluid absorbs a lot of fluid. So for maximum braking power you want new fluid. Brake fluid should be changed every year or two.

lannvouivre wrote:

Chiadog wrote:

dnoishere wrote:...well its a large size bottle that's almost full and should be enough to do the brakes....I don't see it being any different than the master cylinder screw on lid?

Actually, the master cylinder is vented!

And only one way. Stuff goes out, not in.

Oh Lanny, I hate to disagree but the brake reservoir cap on my 2005 is fully vented! If it's any consolation, I did have to "pucker-up" to be certain.

The cap is vented to prevent pressure or vacuum if the fluid level changes. If there's not any problems the fluid level will never change so it won't need to vent. So 99% of the time it is sealed. I would personally just get new fluid but honestly I don't really think it would hurt.

gtv237 wrote:If there's not any problems the fluid level will never change so it won't need to vent. So 99% of the time it is sealed.

Brake fluid level drops as the pads wear down. Clutch fluid in a separate reservoir can go up as the clutch wears.