Back when my bike had 17,000 miles on it the service man at the dealer, one of the associates at our esteemed importer, one of my manufacturing buddies, and the self-appointed expert down the street all insisted I should switch to ATF in the primary drive. Against my better judgment (I have to admit) I decided to try it.
I have just had the primary drive apart again, at 29,000 miles, and cannot find any appreciable wear in the primary chain. The shop manual calls out 190 to 191 mm across 21 pins, with a service limit of 195 mm. Averaged across several overlapping runs of the chain I do not find that the length has changed at all from 190.5. The loosest run is within spec. The friction plates look like they did the last time, with nice sharp cuts and no hint of glazing.
There are tight and loose sections, as always. Also, I think the 5 to 6 mm of slack called out in the shop manual is too tight, so I used Kentucky-windage finger pressure. If I had not taken the assembly apart, I would have just left the adjuster where it was.
I had been using 15W40 (called out in the shop manual) in the winter, and 20W50 in the summer, and had been griping about how hard it was to find neutral when coming to a stop - which was why these guys suggested the ATF.
I've seen some posts recently about ATF or not, so decided to throw my results in there.
Bye-th-bye: if you ever inspect the throw-out bearing or the outer clutch disc closely, you will think twice about sitting at a red light holding the clutch in.
Good luck.
Paul