I ran 100 gallons of 10 year old diesel out of our forward holding tank (converted to fuel by PO in 1992 and then disconnectied in 1995 but never emptied of fuel) in our boat with no trouble at all - just pumped it with an old 12v Holley fuel pump into the forward main fuel tank which had around 150 gal of fuel in it at the time. No treatment of any kind and it ran without any problem at all. All I did was look at it and burn some on a piece of cloth to see if it burned exactly the same way as the fresh diesel. Looked fine to me.

I suppose you can do serious tests and, if it makes you feel more comfortable, that's great. On the other hand, you can make yourself crazy overscience-ing a lot of things...