,,,For a generator in Florida,,,drive down the road and their was literally a blown up generator at the street for the trash man, in front of every single house in my neighborhood.
The lesson learned here is that oil breaks down and gets consumed, especially if you don't change it. A 40 weight will offer a larger margin of error should your maintenance lapse.
The IDEAL generator oil in Florida is 15W40 or SAE40,
CORRECT! Generators, especially hard working post hurricane generators really get the oil hot. One cannot expect thin, conventional oils to hold up well for this use. Even with frequent changes.
I choose M1, 15W-50 for my hard working generators. I learned my lesson the hard way with 2 Honda water pumps (dewatering my lot prior to construction) Both engines got so hot, the oil was unable to sufficiently lubricate and catrastrophic failure resulted. Level did not drop, but viscosity did. (remember, the pumps worked in an unimproved, mid summer, wet lot, pumping day and night. Little airflow, plenty of load) Neither pump made it more than a few days, despite daily oil changes. I knew right away they were going to fail, as the oil was full of glitter.
My Subaru generator has months and months of use on it. Both building my home, and the 2005-2006 and 2017 (4ea) hurricanes. In 2005, we were without power for 6 months. That generator was one hard working little beastie. M1, 15W-50 was a smart choice.