People with horses use it to cover lacerations. When this happens, soap molecules can't do their jobs any longer. Instead of being evenly dispersed in the water, calcium or magnesium tied soap molecules clump together forming soap scum. As this reaction happens quickly, enough soap must be used to neutralize these metals first before additional soap can do any cleaning. Borax will neutralize these mineral salts leaving the soap to do it's job.
Soap is a good lubricant by itself and is added to petroleum oil making grease.
Try rubbing soap on the contact surfaces of a sticking drawer or door. I get my fully hydrogenated soybean oil from US Foods Corp in 50 lb cubes. For general, small scale soap making use a shortening such as Crisco. For Hobbyists or casual soap makers use solid crystal or flake lye such as Red Devil and mix it yourself in water. My color comes from Dixon Crucible Colorart tempra powder, whipped into a roux with a little melted shortening.