When we were trying to pay our house in full I saved every dollar I could. I use to make the same soap as StinchnRipper and has the same ingredients as the link. Mine never separated like that one in the link, it was creamy though. (Grating the soap was a chore).
It left a coating on the clothes especially towels that made them unabsorbant. after a few washing. In fact that is on the recipe I had, to use vinegar to remove the residue if built up. I asked a soap making friend and he said it was the soap as it needs lots of water to rinse clean off fabric. If the bar says soap, it's soap, it if says bath bar then it is not soap. He did not recommend the laundry soap bars for every wash load. I still used the homemade version but every few loads I would use regular detergent to remove the residue. I learned that baking soda added to dishwashing liquid will stop the sudsing. I use it when I run out of dishwashing detergent. Here is the recipe I used
Dishwashing Detergent Substitute
1/4 teaspoon liquid dish detergent and 1/2 teaspoon baking
soda dissolved in 1/2 cup warm water and poured into
detergent cups in the dishwasher.