I agree with most that Rotella, Delvac or Delo are all great stuff for Thumpers....just find the cheapest.
For our two Honda XL600's we are pouring in Delvac 15w40 dino. I would use the Rotella 5w40 on these bikes, but they call for a 1,200 mile OCI...and I ain't wasting synthetic like that. A fill of any of those 15w40's cost us about $6.
PS....come December, I will probably pour in Rotella 5w40 for a winter fill and for a little better protection through the winterized period.