most everyone is going to say use Amsoil. for engine trans
I'm using Valvoline 15w40 for engine and Cummins engine oil filter. only because its free to me
if i had to pay i'd probly use the same.
I used to use Fram filter but not anymore the Crimp leaked on a oil filter i had on my truck once and never used it again. I guess that could happen to any filter maker. But since cummins filter is free i use it
I also use Valvoline synthetic ATF+4 trans oil. Again Free to me so.