Tortoise Shell Conditioner
I’ve been keeping tortoises of various types for years and one of the universal parts of their care regimen is regular soaks in warm water.
Soaking tortoises in warm water helps them hydrate, helps them poop, helps get crusted gunk off of their shells and legs and feet, and gives you a chance to inspect/assess them for health and weight.
Once a month or so, at the end of their soak, I put some homemade shell conditioner on their carapace and plastron (top and bottom portions of their shells).