With small engine oil they can put in certain additives or more of some and thus it might not meet SN but will be better for small engines that are air cooled
Any source for this info?
All my air-cooled OPE gets the cheapest 15W-40 money can buy,
and I have never had any oil consumption problems, much less any oil-related related failures.
It's all the *external* stuff that dies first....
plastic gas tanks crack, fuel pumps fail, wiring and switches fail...
But I have never had any issue that traces back to the oil I use.,