Rotella 15 40. Engine much quieter. Been usin it for 8000 miles.. change oil every 2500 and filter every 5000. 69000 miles on 99 Ultra. FWIW I use Rotella in Crank, Damn near anything in the primary and Lucas Synthetic 80w 90 in tranny. All seems great.
And Wal Mart RARELY gets any of my money also. I cant seem to get my wife to realize what they are really about.... plus she does things for me that makes it ALMOST OK!
Amsoil is a good product for engine oil but there gear lube for the trans 75/90 works ok but they have no primary fluid per say. I run Amsoil V-Twin 20/50 for the eng, Redline shock proof which is 85/90 in trans, Redline V-Twin primary fluid and it shifts so much better & can I find neutral so much easier. Never have tried the Redline V-Twin 20/50 in the eng but may soon. Amsoil is a GL-5 & Redline is a GL-4 product both high standards but all your can do is try them & see what you like best!
Amsoil has everything, ATF works great in the primary.