Just for future reference, there's only two ways oil would affect running:
1. If the generator has a low oil sensor and the oil was critically low, it would not run at all, and you would get an error code or indicator light indicating low oil.
2. If the generator is old-school and the oil was critically low, it would run its little heart out until it seized up, quite possibly accompanied by some disturbing noises such as clanking or squealing, and a loud bang. You may find pieces of the engine's insides, outside.
Just being a little low on oil, even down to the ADD mark on the dipstick would not cause the engine to run differently.
