Each manufacturer has a specific set of criteria it deems necessary for proper function of an automatic transmission. These criteria are given a name, i. e. , Mercon, Dexron, etc. The criteria include properties pertaining to lubrication, hydraulic, and many other properties. These named categories (Mercon, Dexron) may overlap, thus allowing an ATF manufacturer to create one ATF that meets several different standards.
My 15w-40 motor oil has no idea that it is in a Cummins, much less a diesel. It simply meets the manufacturer's requirements for a motor oil.
I use the Amsoil ATF and like it.