Blending oils is for chemists. Anyone else doing so is just messing around. Just like using additives is a fools game, designed to separate you from your money. Remember Slick 50? Synthetic blend oils (semi-synthetic) are no better than conventional oils that they are made of. Blended oils were designed by marketing departments as a way of charging more for their cheapest products. Don't be fooled by their games.
Use an oil that meets or exceeds all the manufactures requirements. Make sure the oil gets hot enough to evaporate moisture - above 80C (180F) regularly. Hot oil is good, cold oil is bad. Change the oil and filter more often if doing short rides, city riding, cold weather, dusty or sandy conditions, etc. If mainly riding highways, and long rides, the oil change interval can be increased.
Shell's Rotella T 15W40 and T6 5W40 Synthetic are widely available in North America, meet JASO MA spec, and are reasonably priced. I personally use T6 in my DOHC with virtually no oil consumption over a change interval. And the 30+ year old seals on the engine haven't started leaking, despite all the dire warnings on the internet.