I would like to change the oil and not in the nut from under the engine any subject of the site in writing or photo of the place. Thank you very much for the help
It is not a nut, it is a large screw that is located in the lower back of the crankcase.
The crankcase is a large rectangular piece, of sheet metal that occupies the entire lower engine and its mission is to cover the crankshaft below and to house the engine lubricating oil.
Anyway, if you still have doubts, throw a photo and open it to the forum.