Well by me "that guy" is OK, because he's come back and modified his thoughts, but his firsts thoughts aren't that bad, because oil was low, and a "nearly quart" added, which is a good fill, so I doubt there was any excess fuel flooding into the sump. But of course his second statement is the best thing to do. Start a fresh with the correct amount and GRADE of oil and see how you go after a run next time. Be sure to let it cool down on level concrete whilst you have lunch and check it's level.
I noticed the level down a bit on my 35 year old 4hp briggs the other day and recall topping it up once recently, so I had a decent look underneath when I washed it, it appeared the crankshaft seal was wet, so likely it's spraying it out whilst I mow, as well as burning a little. So if you don't have a win in finding where it's going, (if it disappears) do a degrease underneath and see what you find.
