I've seen this before. Take the valve cover off and pour several quarts of oil directly onto the valvetrain and oil galleys. Drain the oil and search for your nut. If you don't find it take off the pan and windage tray and it will probably show up.
__________________
Don't bother giving me "rep", I won't return it and I think it is stupid.
Gracie Barra Clearwater
Gyms in Clearwater, St. Pete and Port Richey
pm me if you are interested in trying a free class at any of the gyms.