I s'pose I outa mention that 50 & 100:1 oil mix ratios aren't limited to "exotic" synthetic brands like Opti & Amsoil nor discouraged by all manufacturers...
Since sometime in the 1980's, Yamaha Performance Marine started running 100:1 mixes in their smaller two stroke outboards (100hp & under) & 50:1 in the larger ones (up to 250hp)... this isn't owners or repair techs "experimenting" nor is it a "recent" development, it's just not common knowledge because they're often injected systems preset that way from the factory
by Yamaha & if you mess w/those you will
void your warranty lol
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.
For those "experienced" boat owners that choose to ignore the owner's manual and their technician's advice because it "doesn't make any sense" to them despite the fact Yamaha is one of the pickiest engine manufacturers regarding warranties - they make a product called Yamaha Ring Free Fuel Additive
to clean all the gunky build up & carbon from their poor engines... it works quite well actually.
Other manufacturers run 50 & 100:1 injector setting too, I'm just most familiar with & have ready access to Yamaha - while they don't offer their owner & tech manuals freely online (they want you to pay for them for some reason heh), I'd be more than happy to take a pic or two if a google search isn't satisfactory...
...and if you think Yamaha is full of it & has been for over thirty years... well, I dunno what to tell ya