Unfortunately, with these items, I buy with the intention of using when my maintenance kit needs replacing. However this may be 3/4 weeks away or even a couple of months. I have found recently on my 8560 maintenance kit, no silicone oil, the lubrication that the printer needs. It is hard then to start proceedings against the seller. I would like Xerox to print a best by date on their product and also advise on storage, (Not storing these on their end) as the silicone oil runs to that end.