4lbs Washing Soda (laundry aisle)
4lbs Borax (laundry aisle)
4 cups (or 32oz) Oxy Clean (store brand is fine)
14-16oz bar of Soap (I used Zote, can use FelsNaptha or Ivory, just be sure it's soap not a cleansing bar)
Essential oil (optional)
Grate the bar of soap (I bought a grater just for this, a finer grate than I use for cheese, but not that micro fine kind). Dump everything into a garbage bag and mix it up. Then I cut the corner off the bag and poured it all into a glass container.
Use 1-2 tablespoons per load. Safe for HE washer.