How old is too old for brake fluid?

[oil pan 4]

I tried searching and all I found was posts about open brake fluid and far older bottles (10 year old) brake fluid.
I've got sealed plastic bottles of Prestone dot4 brake fluid from i was going to gueas was 2020 at the latest. Then upon closer examination I believe I found a date code indicating the 159th day of 2022 so not terribly old.
I'm in New Mexico so relative humidity is usually only above 80% maybe a dozen days a year and is usually between 15 and 35% most of the summer and is nose bleed inducing during the winter.

 

[JayhawkRoy]

From what I can read, brake fluid sealed is good for approx 5 yrs.

 

[crashz]

Sealed, I'd say its still good. Opened and capped, I'd recycle it.

So if I open a bottle to use in a brake or clutch system, I try to flush that system and use the majority, because I know I won't use the rest of the bottle in a reasonable amount of time (like a few weeks).

 

[nwjones18]

If they're sealed I wouldn't think twice about using them myself. I've begun flushing brake systems more routinely, but we have lots of old cars in the family running 10-20 year old fluid that sure seem to stop fine... I think everyone flushing the fluid every 3 years is a bit overkill. I do have one of those brake fluid testers, not sure how much I trust it as I've never seen it say any actually has to much water in it.

 

[oil pan 4]

If they're sealed I wouldn't think twice about using them myself. I've begun flushing brake systems more routinely, but we have lots of old cars in the family running 10-20 you fluid that sure seem to stop fine... I think everyone flushing the fluid every 3 years is a bit overkill. I do have one of those brake fluid testers, not sure how much I trust it as I've never seen it say any actually has to much water in it.

Yes the 2 I found were sealed.

 

[oil pan 4]

From what I can read, brake fluid sealed is good for approx 5 yrs.

Probably at least that since there's plenty of vehicles running around with greater than 5 year old fluid in their brake systems.

 

[oil pan 4]

Sealed, I'd say its still good. Opened and capped, I'd recycle it.

So if I open a bottle to use in a brake or clutch system, I try to flush that system and use the majority, because I know I won't use the rest of the bottle in a reasonable amount of time (like a few weeks).

Oh I take my unsealed brake fluid bottles that I know im not going to use into work and they'll get used within a few months at the most.

 

[crashz]

I enjoy the posts you have about the equipment maintenance there!

 

[oil pan 4]

I enjoy the posts you have about the equipment maintenance there!

Nothing really that interesting any more now that ive been running things for a while and I think ive found the worst of the neglected equipment.
Ive got a cummins 6.7 oil filter that will have like 3 oil changes on it.
I'm expecting to find a whole lot of nothing in that oil filter.