Brake fluid in a can ...

[Kestas]

Perhaps, but the trade-off is that the reservoir doesn't need to be opened to check fluid level. I imagine just opening the metal reservoir once a year would introduce considerably more moisture than can permeate through the plastic reservoir during the same year.

 

[unDummy]

Brake reservoirs are vented. Yep, brake reservoir cap is wide open to the elements. Most people wait forever to bleed their brakes and some worry about bottle permeability. Too funny!

Sorry, I'll stick with my cheap plastic bottles of brake fluid. And, even if they've been opened, it isn't an issue! My 3-month old opened plastic bottle of fluid in my garage has less moisture then most vehicles that haven't been bled yet.

 

[Tones]

Funny, cause AFAIK, all of my newer cars and bikes have had a rubber bladder built into the cap which distends to relieve any vacuum. It is not vented to air that I know of under normal operation.

 

[unDummy]

It is!

 

[bbtaco]

The cap on the brake fluid reservoir is vented to allow the fluid to expand and contract without creating a vacuum or causing pressure. The rubber diaphragm helps keep out any dust or moisture.

 

[JakeR22]

On old cars for sure, the resivoir lid is a solid piece of steel. No holes or vents. And it clamps down tight to the resivior.

I don't think the resivoir is open to the air either.

 

[y_p_w]

I would think that most cans are plastic lined by now. I know that aluminum soft drink or beer cans are plastic lined. Coke contains phosphoric acid, which would eat through aluminum in short order. Not sure about steel cans, but I would think they'd also be plastic lined by now.

The last time I bought brake fluid, I got (sent by mistake) Motorex DOT 5.1 in 250 ml rectangular steel cans about the size of a can of Spam. The cap was plastic, as were the thread base. It also had a plastic pull ring to break the plastic seal. In the same order, I got Motul DOT 5.1 fluid in 500 ml plastic bottles that they claimed reduced moisture entry. They were also alleged to have been packed with dry nitrogen.