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Once the initial baking soda cycle is complete, the next step is to add white vinegar. Pour two cups of plain white vinegar directly into the washing machine drum. For an optional pleasant scent, you can add 5 to 10 drops of lavender essential oil to the vinegar mixture. Close the washing machine door, then run another cycle on the longest and hottest setting. This vinegar-based mixture will help to disinfect the washer and remove any remaining film or odor.