I would say that on your engine, it would be fine if extended maybe 500-1000 miles. I wouldn't go much over on your tranny though because the tranny isn't like the engine in which you can easily replace your filter so that it doesn't become clogged.
I may be wrong on this, but that's why I wouldn't extend the tranny application by much.
Cleaning mileage in gas or diesel engines. Auto-Rx Applications mileage requirements should no be extended over 25 % of the normal application mileage.
Just to let you know, once I ran 6 oz of Auto-Rx in a transmission for more than 12k miles/one year. I FORGOT that had put it in my father-in law's high mileage 1996 Chevy truck until I saw it written down in his maintenance book a year later when finally changing/flushing the transmission fluid. While I am not recommending this practice, I can say that it did not damage anything and that all is well in his transmission to this day.