I was perusing the razors on ebay and came across this. Beyond what I would consider one of the many proper uses, it goes on to say "Many clean faced men rub 3-in-One oil on their faces before lathering. It softens the stiffest beard."

While I am not going to give this a try I did find it interesting.

1924 3-in-One Oil Ad Straight Razor Clean Faced Man? | eBay