My engine blew VERY early on 40:1. I'd be quick to blame any failures on these things being cheap before I'd blame any gas/oil ratio with any brand. Or just other factors like environment like someone else mentioned. It all seems to be a very inexact science(the end user part of it) that just decides to blow up in your face every now and then.
But, I'm new to this. My new engine will get something other than Havoline is all I know. Just because my engine died while running it. Nothing personal.
Even for the tiny (3-25hp) premix engines it states quite clearly in the owner's manual to use 100:1 - they do recommend their proprietary Yamalube brand, naturally.
I'd like to throw out the idea that a better machined/QC engine from a name like Yamaha or another big 'un could very well be(and always have been) built to tighter tolerances and so tolerate running with less protection. Good enough for me to try it though. Hopefully I don't toast another cylinder and piston.