Shelf life of opened fluids

[mclasser]

How long can these fluids typically last once they've been opened?

-Motor oil
-ATF
-Coolant
-PS fluid
-Brake fluid

Brake fluid shouldn't be stored for long but I've used 2 yr old opened bottles of the other fluids for top offs w/out issue. My garage goes through regular seasonal temperature fluctuations but I make sure the bottle caps are on nice and tight.

 

[HTSS_TR]

Brake fluid can be stored for about several months with cap real tight. Other fluids are okay for several years, 5-6 years ?

 

[147_Grain]

Brake fluid is hydroscopic, meaning it absorbs water. The other fluids generally don't have this problem.

 

[BrandonVA]

refrigerated, frozen, room temp???

 

[another Todd]

Originally Posted By: 147_Grain
Brake fluid is hydroscopic, meaning it absorbs water. The other fluids generally don't have this problem.


It's not hydroscopic when capped tightly, as it needs access to moisture in order to absorb it. It'll be good for years if capped tightly, just like the brake fluid in your vehicles brake system right now. It doesn't go bad in months, so neither would fluid in a capped bottle. Now, if left without a cap or a loose cap, then it will be bad in short order.

 

[NHGUY]

Hygroscopic.

 

[another Todd]

Hygroscopic is correct. I guess I've been saying it wrong for about 30 years, and nobody noticed until now. Well done NHGUY!

 

[Doog]

All are good for one year if not subjected to freezing.