Having unscrewed the drain plug with a 12 mm Allen key, we drain the used oil. Then we screw the plug back in place, having cleaned its magnet from steel shavings.
We fill the oil through the hole closed with a plug, in the rear part of the beam, having unscrewed it with a 17 key.
If the oil drained from the gearbox housing is dark in color or metal particles are visible in it, it is necessary to flush the gearbox. To do this, pour about 1 liter of a mixture of transmission oil with 20-30% kerosene or diesel fuel into it. Then, hanging one of the rear wheels, engage 1st gear and start the engine. After 2-3 minutes, drain the flushing mixture and pour 1.3 liters of transmission oil into the gearbox.
The oil level should reach the lower edge of the filler hole.