Discard Oxidized Rodinal !
Rodinal concentrate indeed has a long shelf life. However it slowly turns brown, and the material slowly loses its developing power. Unless you are in a hurry to develop a film, or don't have time to go to downtown to buy new bottle of Rodinal, you may still use it, but you reduce the dilution ( ie, use more Rodinal in same amount of H2O) or extend the development time.
However the best thing to do is to through it away.
Rodinal is dirt cheap, why save a few pennies and risking ruin your precious negatives ?
One day, you may find that your negative developed with oxidized Rodinal is so thin, even grade 5 paper cannot print it !
(posted 8659 days ago)