I come from the industrial hydraulics world where oil is everything. All of the major manufacturers recommend, with some rounding errors, that the oil, AT OPERATING TEMPERATURE, be between 16cSt and 36cSt. Additive packages are important, but we expect properly designed equipment to last well over 100,000 hours, 200,000 is not unusual at all. I've many customers who maintain oil temperatures below 60C (140F), keep it clean and dry, and don't even consider replacement until 50,000 hours.
It's the dilution and water that cause most of the problems in internal combustion engines with short cycling and temperature cycling.
My SINCERE kudos to automotive power plant engineers and lubrication engineers for the amazing work they have been able to do.
All to try to have 16cSt-36cSt from below 0F to above 240F, or as near as possible at an affordable price with a reasonable lubricant.