I've got some WD2D+ that is probably 18 months old, still 3/4+ full. I haven't used it in a while, as I had found HC-100 dil H/HP5 to be a great combo. I just shot my first Classic 400 and thought I'd give WD2D+ a try. Photographer's Formulary was vague about shelf life, something along the lines of " a good while." Does anybody have more specific information, or should I just pour it down the drain? Maybe I'll try PMK next time, it seems to have a great shelf life.