[header] How to make fabric softener [title] Combine 1 gallon (3.8 l) vinegar with 25 to 30 drops essential oil. [step] Stir the essential oil directly into the container of white distilled vinegar for a minute or so to ensure that the two liquids combine well. [substeps] Note that the essential oil is not necessary. 
The vinegar is the component responsible for softening clothes. It strips away residue on your clothes that would otherwise make them stiff, and it has properties that can break down some of the minerals found in hard water supplies.