Do U use Driven Hot Rod oil or Amsoil Z Rod?

Does anyone have experience with either the Driven Hot Rod or Amsoil Z Rod oils? If so, what viscosity are you using and in what engine and power range? I know both brands make some race only oils, but don't think that's what I'm looking for with a street strip 440.

I just started using Z Rod. I'm using 20-50 in a 540 hemi that I take to about 6k. I just made the switch, and can't say I've noticed anything one way or the other. I put my engine together from parts from Tim Banning at FHO, and this is what he recommends, so why not?

I have being using Amsoil 20-50 zrod for years in my solid lifter 451.Roughly 550hp.

Thanks. I don't want to run 20w50, but will check out the lighter weight oils.