I think Mark used conventional 5W-30 and 10W-30. I suggested otherwise, but he followed the owners manual. The result was (just like my 2 Honda water pumps) engine failure on the exact oil the manufacturer requires.You wouldn't happen to know if that was conventional or synthetic 5w-30, would you? It's not that I would run either in one of my generators up north here, let alone in your climate, but inquiring minds want to know.
I've not posted the story of my Honda water pump failures recently. I was de-watering my "jungle-like" Jupiter Farms lot, so the environmental people could make a positive wetlands assessment prior to construction. I used the correct oil and ran the pumps 24/7 with daily oil changes. The first pump destroyed the connecting rod and I chalked it up to a bad engine, which was replaced under warranty. The second engine failed in the same manner and I returned it for a refund, as it was not cheap. The Honda dealer was amazed, and compliant. I purchased a Kawasaki water pump, and chose M1, 15W-50. I still have the Kawasaki pump. It powers my fire hose. The stagnant air around my water pump allowed the engine to overheat it's oil. Which resulted in insufficient film strength and rod failure.
Post hurricane generator use is similar. It can, under the right conditions, heat the oil beyond it's ability to protect.
I learned my lesson early on. Bought a thermocouple in more recent years, and was astounded at the small engine oil temps. 265 deg F was the normal oil temp. By way of comparison, my Cessna has a oil temp redline of 240. And it uses 50 viscosity oil, not 5 viscosity.