i had some d76 solution for a few months now and it is still clear...

Color is not a reliable test of activity. Some developers will
become brown from oxidation but some can become inactive and remain
clear. Generally, D-76 will discolor if it becomes oxidized and, again
generally, will be active if clear. The only sure test is to develop a
scrap of film and check the density. A bit of film fogged in room light
should be quite dense black after about five minutes in full strength
D-76.
Kodak gives the shelf life of mixed D-76 in a filled container as
six monthes. My experience with is that it will last much longer even
in a partially filled container. It is a very reliable developer.
Dektol is slightly amber colored when fresh mixed. It discolors
much more with use and with age than D-76, perhaps because it has much
less sulfite in it. Sulfite tends to prevent oxidation of the
developing agents.
Some developers, Amidol is an example, will become inactive even
though they remain clear. I recently experienced short term failure of
some Xtol which also remained clear although its developing activity
was very much reduced.
Some other developers are amber when fresh, I use Agfa Neutol Plus
print developer which is honey colored out of the bottle.
If the powder for a developer mixed from powder is tan or brown its
a good indication its oxidized and no good. Badly oxidized Dektol will
have a quite evil odor. This stuff should be tossed.
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com

It will turn color eventually but that is not a reliable indicator.  In
fact, by the time a color change is evident, it is way beyond useful.  Dump
it!  Its not worth the price to probably screw up your negatives.

Truly, dr bob.