My Briggs & Stratton P2200 inverter-generator (Engine is 111cc) I got recently says to change the first oil after 10 hours of run time.
They want certified detergent SF, SG, SH, SJ or higher, but recommend their B&S Warranty Certified oils for best performance.
No additives!
Viscosity to use depends on outdoor temperature Usual chart for that given. Interesting on that chart is that Synthetic 5W30 covers the whole band of temperature, while the other oils have limited temp ranges for their use.
Says change oil more often than every 100 hours if in dirty or dusty conditions.