The sump plug is accessed from underneath the car
You may need to remove the undertray
Undo the retaining bolts using a 10mm socket
Don't forget to place a suitably sized receiving tray beneath
Use a 21mm spanner or socket to carefully remove the sump plug and fully drain the oil. When the sump has emptied, wipe clean the sump plug area with a paper towel and re-fit a new sump plug and washer. Do not over-tighten
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