Yeah right. An additive. What a scam. The only car I know of that requires transmission fluid changes on a regular basis are the Northstar Cadillacs in the 2000's year range. I think it is every 30000 miles.
My 2005 GMC truck lasted 108K miles before the 4 speed auto tranny became a 2 speed powerglide.
Had failed to change the fluid at 75k and the transmission crapped out at 108K.
Now I’m driving a Ford, no guv’ment money so that’s good news!