When to discard unused brake fluid?

[edcop]

When should you discard unused brake fluid?

I changed my brake fluid about a month ago and I still have almost a full container of unused brake fluid left.
I was going to change out my clutch fluid today with the left over brake fluid from a month ago but heard that you should discard any unused oil within a week.
Is this true?

 

[edcop]

unused oil within a week.
Is this true?

SORRY, I meant unused brake fluid

 

[OldMan]

Once a bottle is opened it absorbs moisture and since the stuff is so cheap why bother keeping it around?

 

[outlawbusa]

I always keep the old bottle around to know exactly what I was running...that way I can purchase the identical fluid next time. I used what the shop recommended for high temp, a race dot 4 fluid.

 

[edcop]

Once a bottle is opened it absorbs moisture and since the stuff is so cheap why bother keeping it around?

I wish it was cheap, I paid almost $20 for this stuff and its almost full but been sitting around for about a month:

 

[OldMan]

I wish it was cheap, I paid almost $20 for this stuff and its almost full but been sitting around for about a month:

buy regular DOT 4 brake fluid, sold at any auto parts store, it's like $5 for a quart, you don't need anything specific for motorcycles.

 

[IG.]

Wrong. So long as the bottle is sealed tight and kept in a dry place, it will stay unaffected for many months.

Brake fluid gets darker as it absorbs moisture (by design so it is visible). If it's as clear as new, you are good to go. I've used a year old fluid with no issues.

 

[Twobrothersbusa]

This is an interesting question. I am in the same boat. Used a bit of a bottle of Motul and can't stomach tossing the unused. Anybody with EXPERIENCE in this would welcome the info. The better fluids make a big difference as I have boiled stock fluid in the Busa at the track.

 

[lil charlie]

This is an interesting question. I am in the same boat. Used a bit of a bottle of Motul and can't stomach tossing the unused. Anybody with EXPERIENCE in this would welcome the info. The better fluids make a big difference as I have boiled stock fluid in the Busa at the track.

I used to be a Master ASE certified tech so let me tell you how it is, I saw used to be because you got to renew they every two years and I’m no longer in that business so I let them laps. It starts to absorb moisture as soon as it has been opened. If you live in a dry area, like Arizona which has an average humidity level of about 8%, you can keep it for about a month. Other areas with high humidity levels should follow the manufactures recommendations of one week. It is true that brake fluid will change color with moisture; however, it takes a lot of moisture to change the color. Just you everyone knows, water is very bad for your system, like air it compress under pressure. When you grab that lever you do not want that fluid to compress, which is what gives you that spongy feeling, you want the fluid to act as just like it was a solid rod from lever to pads without any compression. So toss it if it’s a month old. Is it really worth the risk of crashing over a $20.00 bottle of fluid? I know it sucks wasting it like that but you should have done both the brakes and clutch at the same time.

 

[mattd428]

I used to be a Master ASE certified tech so let me tell you how it is, I saw used to be because you got to renew they every two years and I’m no longer in that business so I let them laps. It starts to absorb moisture as soon as it has been opened. If you live in a dry area, like Arizona which has an average humidity level of about 8%, you can keep it for about a month. Other areas with high humidity levels should follow the manufactures recommendations of one week. It is true that brake fluid will change color with moisture; however, it takes a lot of moisture to change the color. Just you everyone knows, water is very bad for your system, like air it compress under pressure. When you grab that lever you do not want that fluid to compress, which is what gives you that spongy feeling, you want the fluid to act as just like it was a solid rod from lever to pads without any compression. So toss it if it’s a month old. Is it really worth the risk of crashing over a $20.00 bottle of fluid? I know it sucks wasting it like that but you should have done both the brakes and clutch at the same time.

ASE mechanic here as well and he is correct

 

[karnage]

I just keep it in my chemical cabinet in my dry shop and keep the bottle cap tight and never had an issue.