I just realized that two boxes of my C-41B developer replenisher Part C is turning dark. I believe it is a sign that it is going bad. Each of the boxes contains 4 set of bottles. Each set (Part A, B and C) is for making 10 liters. I think I am facing a big loss of developers now. Well, I bought them from a closing mini-lab a few years back. I am witnessing that the chemical even unopened does not last too many years. I have about 80 liters of this replenisher going bad. I mixed 10 liters a few days ago and began to use it regardless. It seems to be working OK at the moment. I have developed 3 220 rolls with this replenish (+ starter of course) and I see no color shift or anything wrong yet. But I know they are going bad very soon. My question is how long do you think it will be OK still? If they are still good for a few months I am planning to donate them to a school. But if it won't last for too long this may not be a good idea at all. I am not sure I can buy part C alone from anywhere. Any suggestions? I guess I will shoot a few more rolls before winter and process all of them with the developer. Next year I will have to buy fresh ones again.