I usually stick with what the manufacturer tells - sometimes you have to follow their updates too.
the 5w30 etc. is only viscosity, e.g. ATF is about 10 weight oil, it does not mean you start to use it in your engine. The major factors is what the oil is capable of withstanding in terms of pumpability, shear strength and pressure, this story first starts with what base stock was selected to use and what minerals/additives were blended in it. e.g some oils that are used in racing motorcycles with shared sump/gearbox have additives in them to aid some traction in the clutches.
now lets come back to general market.
nearly all modern oils are low saps (low sulphated ash, phosphorus and sulphur) - these oils are ACEA A3/B3, C1-C5 and also carry API SM performance compliances. These are meant for diesel engines with particulate filters or petrol engines with monitored three way catalytic converters. Its wonderful as modern engines either utilize roller rocker arms or bucket shim tappets etc.
The problem arises in older engines which utilise flat tappet rockers, like old Honda A,B, D, F and H series - toyota K,Y etc etc etc. You know what to look for. These low quantity additives were very heavy duty EP additives and protected the cam/rockers from early wear out. These old oils also had a higher TBN number but were made of lower quality base stock. The modern oils have moly, boron and calcium are used in the old minerals place but these oils have a lower TBN, meaning they will wear out sooner. But the replacement minerals dont exactly protect like the old HD ones did.
This above problem is also noted and warned against by ACEA, its quite known. Hence please use oils that are specced for your engines. And all oils are blended in mind that your engine will be run at normal temperature and have a working PCV system. If you miss out on these little factors you can pour the most expensive blend made of Group 5 synthetics or even first flash collection in the market and still see early failure.