I use amsoil,mobil 1,red line,motul in the engine. I'm not a fan of mobil 1 simply because it made my top end sound like it had ball bearings bouncing around in there.
As far as the primary is concerned you can save a few bucks by using rotella conventional in it. The primary NEEDS an oil that has a JASO rating on the bottle. The primary doesn't need tge big dollar synthetics,I've used it for years in my shared sump bikes and never a clutch problem.
I use red line shockproof heavy in the tranny. It helped finding neutral,no more clunk going into gear,any gear oil will work though. Summertime viscosity 70w-140.
Now synthetic vs conventional is a big debate. They are both oils,synthetic will last longer between oil changes. It's not magic and isn't going to double your engine life. Maintenance will will extend engine life.
If you decide to go synthetic a 5000 mile oil change interval is fine,if you are going to use conventional a 3000 mile interval is adequate.
There is no magic elixir to keep these motors happy. Just get into a maintenance schedule and stick to it.
Your bike really won't notice the difference.
And I have royal purple auto oil 20w-50 in my bike right now and the top end noise is significantly reduced as compared to mobil 1.
I broke my 106 in on pennzoil 20w-50 and I'm considering just sticking with it. The motor sounded seamless and no valve noise at all.
Your results may vary.

 

I recently switched from Valvoline 20w50 racing full synthetic oil in the motor and primary, and an off brand oil in the transmission. My last oil change, everything was drained and I switched all 3 to Royal Purple 20w50. Shifts better, runs smoother/quieter. I think I found my oil.

 

I use M1 V-Twin 20-50 in all three. No problems, no issues, etc.

It's been said before and I think it's most important. What you use (Syn or Dino) doesn't matter nearly as much as how often you change it.