Mobile 1 in 5w-30 or Valvoline racing oil in 10w-30 seems to work pretty well for me.
People talk about not using a synthetic for break-in (rings won't seat, etc), but that's BS. You need good lubrication for the engine when it first starts & is cold (fairly thin), then a very good high temp film strength when it's hot & running hard. Don't use additives (zinc stuff is really bad for most oils & can do damage when used with some oils) but use good oil which is made right from the manufacturer with proper additives. Just my $.02 woth, & YMMV.