I just processed a very important roll of 35mm Delta 3200 in FX-39, and rather than risk disaster, I used a brand new bottle of developer. I've seen many references on APUG to FX-39's relatively short life after opening, but I have used it several times without a problem when it had changed to quite a deep yellow colour, quite some months after its first use. Today's roll was fine in fresh developer, but can anybody shed some light (or shed a yellowy colour) on how long opened FX-39 really lasts? Thanks in advance.