How often do you take the engine shroud off and blow out the cooling fins? I must confess I never did in 23 years with my F510 and did finally have exhaust valve issues. Right before that I replaced the valve cover gasket as it had hardened and cracked from the heat, I belatedly figured out..
+1
Cleaning the cooling fins is just as important if not more important than changing the oil. I've seen so many engines damaged due to mouse nests plugging the fins.
I service a few machines for landscape companies. Most know almost zero about motor oil, and put in whatever the cap says or they think it should take. 0w40 is perfectly fine for most small engines, many manufacturers even recommend a 5w30. I'd definitely prefer a Euro 0w40 over any run of the mill cheap 5w30. Most places that service and sell equipment sell whatever oil that manufacturer provides them with, or whatever cheap bulk oil they can get.I am not going to argue with you. You are one of these guys who knows everything. But if you talk to anyone that makes a living as a contractor, or talk to the folks who sell parts and service, no one uses 0w-anything in air cooled equipment. If you want to use it in your machines, that is your business but be aware it is not the recommended viscosity for almost any of these machines.
Don't overthink small engine oil. Small engines are not demanding on oil. All of my air-cooled stuff runs lower oil temps in summer than my BMW does, and they are all very simple engines with low valve spring pressures. No high zinc special oils needed, just change it frequently and keep it full. I've worked on equipment from people with all sorts of beliefs about oil, from only running 5w20 in them for fuel economy, to 20w50 and everything in-between, including a guy who only uses non-detergent SAE 30, and they are all fine.