I just flushed my system with some Motul RBF 600 which had been sitting sealed in the garage for over 6 months and it seems fine.

 

If the cans are unopened you should be fine for at least a year. A couple of years might be pushing it. I'd try it, you'll know pretty quickly if it's not up to par, and you can just change it again.

 

Probably too late to answer this by now, but you shouldn't use brake fluid that's more than 2 years old, even if its' in a sealed container. I wouldn't even try to use brake fluid "a few" years old.

 

Probably too late to answer this by now, but you shouldn't use brake fluid that's more than 2 years old, even if its' in a sealed container. I wouldn't even try to use brake fluid "a few" years old.
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Actually, not too late at all... the brake makeover was in spring 2002 (now that I have the dates on the cans (12/2001), I can backtrack).

To the disposal it goes.