Sno-Seal is a natural beeswax waterproofing which protects leather from rain, sun, snow, and salt. It dries to a solid wax that "stays put" in the surface of the leather so the protective film lasts longer. Greases, oil, and animal products permeate through the leather and clog the pores, filling natural spaces that are supposed to allow perspiration to pass through and insulate.
In my experience use of animal fats weakens and rots leather. Tanneries work hard to remove fat to preserve the leather, so it's hard to imagine why you'd want to put it back on.
Before waterproofing is applied, the boot must be clean and dry. Heavy dirt is scrubbed off with a wet brush. Light deposits can be wiped away with a cloth moistened in water, mineral spirits or Stoddard solvent. Solvent has the advantage of evaporating quickly so you don't have to wait before applying the waterproofing.
Another advantage of Sno Seal is that it does not soften box toes or heel counters of paratroop jump boots or mountaineering footwear which requires rigidity for support. It's the very best stuff for treating snowshoe bindings and it works in sub-zero weather when rubbed into sewn tent fabric seams and it doesn't crack, like the common liquid plastic goop does.
I also use it as an expedient protective film against rain or salt spray on my hunting firearms in foul weather and even as an expedient bullet lube for Maxi-Balls in my .50 cal. blackpowder muzzleloading rifle! And as an emergency wound cover and salve. Versatile stuff! I carry a tin in my survival kit.