Don't anyone take me the wrong way I'm by no means a lubrication specialist, but you can find something somewhere on the internet to back your view on about any subject. I remember reading an article a few years ago online that said 15w40 was probably the best trade off of any weight available. Just today I found this.
https://www.machinerylubrication.com...518/motor-oils I guess the main reason I stick with 10w40 in my vehicles is because over a 43 year period and approx. 1M miles they've worked great for me. Living in KY our climate as a general rule falls between 0*-100*F and 10w40 specs fall within that range. I think I have either some 5w30 or 10w30 or possibly both in the garage that I bought a couple years ago that if I live long enough I'll eventually try but, at my age it's likely my son will end up using some of the oil I've purchased over the past few years. I'm still using 10w40 Exxon Superflo in my '97 Ford Escort that I bought in the '90's so I'm trying to use up the older stuff before moving on to the newer stuff. I started using the Superflo at the first oil change and have been using it ever since. I know now they say it's safe to use multi viscosity oils in small engines but for years they advised against it because of excessive oil consuption. I still use 30w in my lawn mowers.