Guess you missed the part about better reduction in foaming and corrosion protection in humid environment
No , I didnt , I think that largely bollocks that Outboard manufacturers tell you to get you to buy their overpriced oil .
I drive my cars in the rain ,I ride my quad thru 2 feet of water and dont have issues with humidity inside my motors ....as for foaming ...news to me ...Ive never seen foam coming out a breather .....maybe if I overfilled my motors ...but no .
I have never ...ever.... had an engine fail due to any oiling issue .
I gotta say that some of the motors I have seen on this site .....I would be ashamed to be caught with my motor is such poor condition ...dirt and corrosion wise , but thats on the outside .
Im not saying your all a bunch of dummies....far from it , Im just not buying into the whole special oil for small ( like not fishing boat diesel or ship motors )marine engines . We get the same thing with motorbikes .... the "gotta use motorbike oil " .....once ,in about 1986 I put castrol GTX (car oil ) in a bike ...that I bought at a motorbike shop ...and the clutch slipped . For years I used Valvoline XLD in everything ...now I use Penrite HPR 5 or 10w40 ......even the ole Briggs and Stratton mower gets it and that motor is 36 years old now .

Im going on a bit coz its better than having to talk to my sis-in-law.