Put a container for used oil under the crankcase
Unscrew the plug and drain the oil from the crankcase
It is better to drain the oil from a warm engine.
Replace the drain plug.
Change the oil filter or filter element.
Unscrew the filler cap and fill with fresh oil. The oil level is controlled by the oil level indicator (dipstick).
Fill oil up to the “P” mark on the dipstick.
Then tighten the plug, start the engine and let it run for a while, turn off the engine and wait a few minutes until the oil drains into the crankcase.
Check the level on the dipstick, add oil if necessary.