Oil on leather shoes...?

use corn starch. If it's old, put some corn starch on there, rub it briskly until you feel the heat and keep at it. Replace soiled corn starch as needed. The heat from the friction loosens the oil and the corn starch soaks it up faster than the leather can. If it's a big stain, a shoe or leather shop can do an extraction on it but the cost of that may exceed the cost of your shoes. Worst case scenario... get new shoes or stain the entire shoe in oil... or just live with it.