However the principle that it's changed regularly is a good one - of all the (European spec) cars I've owned, the transmission fluids needed changing about twice as often if regularly towing than if not towing - BUT - our Australian and North American contributors are typically towing much heavier trailers than we do in Europe.
In the past, it was easy to check ATF condition by examining the fluid on the dipstick - but "progress" has removed that facility.
