"In general, what is the shelf life of Neutol ECO?"
In Photo chemistry there is unfortunately no such thing as a definite shelf life.
It is organic chemistry and many factors have an influenece.
We have published a longer explanation about it in German here:
http://www.adox.de/Photo/haltbarkeit-von-entwicklerkonzentraten/
The red color may be an indicator for an edgy status of the developer but it may also still work fine. It is definitely not fresh anymore.
These developers turn darker than conventional developers but
ususally still work fine.
In your case the info we lack is which packaging size you have bought and if it was stored the entire time with the lid facing upwards in a cold and dark place.
In short: A 1 Liter concentrate should not have gone bad after just one year but we also do not guarantee a longer timespan. The smaller bottle sizes have a shorter shelve life. We do tell this to our customers and make them aware of this. Usually it is not a problem because the customers buy the smaller amounts to use them up immediately (and this is what they are for).
Next to this we only produce them on demand almost every day to keep the chain short.
We constantly improve our products and thus we have upgraded our bottles in the past 2 times. The new bottles with the rounder neck as in the images on the website preserve the chemicals better (at the offset of a higher price) so the keeping time will benefit but we are not yet at the end of live of such a bottle so we do not have a clear guess yet.
I expect a one liter concentrate in the new bottles to last at least 24 months if stored corectly in an unopened original bottle.
Mirko