Jim,
We rent all of our row crop land out to different people and use our tractors for bush hogging, road, path, firing range and lawn maintenance, so we don't store large quantities of fuel in tanks like farmers. We use plastic fuel containers and periodically completely empty them. We have, however gone two or three months before using it. We have tractors from 23 to 80 horsepower and have not had any problems, so I don't use an additive.
My brother uses an additive in his tractor, but it doesn't get a lot of use.
I do use HEET ESO for diesel occasionally.
I would never advise anyone not to use an additive, I just haven't had the need to myself. As mentioned by some others, I only use from a place that sells a lot of diesel. Hope this helps and will do a little more research. Larry