Cummins 5 year old synthetic oil with 1000 miles - change ?

I can't see how anyone can say it's OK to put 10K miles on that engines oil without knowing waht exact eng and year it is. A lot of Cummins engine didn't have anything near a 10K mile oil change interval.

As far as the acidic thing and old oil, I don't buy it. I once let an old car (1964 Thunderbird) sit for roughly 6 years and then I rebuilt the eng. The bearings didn't show any signs of being eaten by acid.
I can see the reasoning behind the theory but in pratice it doesnt seem to be an issue.