Thanks for all the replies.
It's interesting how different people SF this soap.
The reason why I ask this questions is that I actually made mechanic's soap once with 0%SF, not really knowing why except that the recipe stated it. I gave it to a colleague's husband to use, but she tried it herself and claimed that it cured the eczema on her hands! :shock: In less than 2 weeks!
The soap had turpentine in it. I was really at a shocked when she told me this because I thought a soap with 0% SF and turpentine would dry the heck out of your skin.