Rather agree about the hyper feelings some seem to have about their particular brands. The accuracy of @hattitude 's meme is certainly real.

If folk have a flat tappet and a rather high lift camshaft with a steep ramp angle, consideration to zinc content is important. Our engines don't, and most of the bearings are roller type. About the only real "load" on our engines is heat.

Radically modify the engine, ride it extremely hard, and you increase the load on the bike, engine and oil. Then your oil demands are higher.

 

I just run with Harley Syn3 cause its readily available and it works. Are there better oils, probably but I typically change it out every 4000 miles and oil change frequency is more important than what particular oil you run. As for cost, oil changes and fuel are likely the most inexpensive part of owning a Harley.

 

Gump! You're a damned genius!