I believe developers are more resilient than their reputation. There seems to be some panic about photo chemicals with people almost worrying about their Sodium Chloride going off. That being said yours is quite old. I have some glass ampules of Neofin Red and Blue, which must be ancient. I'll need to test that some time in the next few years.
I had a break from my positive darkroom that lasted from mid June to last Saturday. I left the developer (Adox MCC dev) in the slot processor, which is covered by a dust lid and also some protectan carefully applied. After the first two months I returned to replenish 100-200mL in the hope to make it keep (no printing done). At that point I also dumped the stop bath and probably also slightly replenished the neutral fix in its slot.
Now another three months later I replenished another 100mL before beginning the print session and the results are great. As the level was a bit low to begin with and went lower from the FB paper I added another 100mL fresh dev during the session. The developer in 1+4 dilution is its own replenisher. I similarly replenished the fixer from a bottle of working solution just as old as the tank solution. Each slot has 1.8L capacity.
The developer was slightly slower, with the picture emerging after around 8s instead of 4-5s, heated to around 25 degC. I printed on Adox MCC FB paper. I've got beautiful deep, black shadows from two PanF+ negatives. Seems quite neutral, no blue cast like I got from exhausted/oxidised Adox Neutol Eco on MCP RC paper.
I also have D76 stock solution, which has been around for a bit over a year. It is slightly yellow, so I did a clip test by taking a quick picture in a Minolta X500 and cutting the negative after opening the camera in the dark. I developed the single negative in a black 35mm film canister as a tank. And it came out just fine. So I used the stuff to develop 5 rolls of HP5+. I decided this test would be better than just developing a fogged piece of film in out in the light.
I also have Spur HRX fine grain developer in use, which I opened in August 2016. It is split into two components, though, which probably helps.
Finally my 1+4 solution of Adoxfix was exactly a year old. After the five rolls it hit the count at which I dump it. The stock bottle is three years old and had enough for one last batch. Adox recommends to use up the concentrate withing three months of opening.
After this final batch I will use for b/w film the same neutral fix, which I'm already using for printing. No more acidic fix for me.
So store your chemistry well, use protective gas cover (Butane) and run a test if you are worried.
