Yours is air cooled and runs at 3600 RPM. Air cooled engines have looser rings and will burn oil.
We tailgate UF football games so its several hundred RVs running their gensets all weekend non-stop. My 5500 Onan would burn a quart a weekend.
I highly recommend shutting it down every 24 hours and checking/ adding oil.
Over the last 13,years I have put about 15k hours on three gensets.
Normal for tailgaters.