Recently, it was time to do a transmission fluid and filter service on my mom's car
In my garage, I had several sealed quart containers of the correct fluid, factory fluid, not some generic stuff, FWIW
Now let me add a few details, to make it more interesting . . .
The fluid was at least 10-15 years old, but as I said, the seal had never been broken. Unopened quart containers
The fluid meets the spec listed in the owner's manual
But at some point in the past, the car manufacturer issued a bulletin instructing dealership personnel to start using fluid meeting a newer spec . . . which was, naturally, CONSIDERABLY more expensive. The stated reason was quite logical. They wanted to only stock one atf, for logistical reasons. And the newer atf was backwards compatible.
I figured, since my supply was factory fluid which met the manufacturer's specs when the car was built, I'll use it. Financially, it would have been foolish to throw it out unused.
It would be like if a guy had unused supplies of genuine AC Delco Dexron 3, and decided to not use it, because it's been superseded by Dexron 6. Never mind that his truck is a 1992 Silverado, and Dexron 6 wasn't even around.
In case anybody's curious . . . this wasn't the first time I used atf from old, unopened, sealed containers. I did it a few years ago on that same car. No ill effects. And now it was time to do it again. Unfortunately, I've now used up my supply of factory atf. So I'll actually have to buy atf next time.