Grate the bar of soap with a cheese grater.
Add the grated soap to 4 cups of water in a pot on the stove.
Heat on medium until dissolved. You can use an immersion blender at the end to help it along if you like.
Once the soap is dissolved, remove the pot from the heat and add the borax and stir.
Add the washing soda and stir. It will be thick and a little harder to stir at this point.
Pour the mixture into the 5 gallon bucket and then fill the bucket 3/4 of the way with WARM water. Make sure it is warm or on the hotter side to help dissolve the ingredients. Give it a good stir, put the lid on and let it sit overnight.
In the morning take the lid off and stir it.
Pour some into smaller jars and add your essential oils to those smaller jars.
Use 1/2 to 3/4 cup of laundry soap in each load of laundry.