2011 Ford Ranger with manual transmission with 91k miles. I just did a fluid change from M1 ATF to Amsoil Manual Synchromesh Transmission Fluid 5W-30. ATF is what is recommended. With only 12.5k miles on the ATF, shifting was notchy from day 1. It would resist going into gear and then suddenly engage. There was a shocking amount of iron particles on the magnetic drain plug. There was enough that the wear particles had a wave pattern on the magnet. After the change, shifting immediately felt nice and smooth. So far I am very happy with the change and even more so after seeing how quick wear was occurring with the M1 ATF.