To understand about leather think about this, remember when you were a kid making mud pies and once they dried out they cracked up, because the water was removed. Same thing about leather once the oils or even partly removed leather will start to crack. Same principles apply to vinyl covered areas like dash boards. Using any type of cleaner to clean leather is not good because oil is being taking out with the detergent so the oils is being replaced with water and when the water evaporates from the leather it will start to shrink, the more oils taken out the more it shrinks to the point it will crack.
Cleaning leather is best cleaned with a leather conditioner that will replace the old dirty oils with clean oil. Sounds easy right? there is a trick to cleaning leather, and the trick is use lots of clean rags and lots of conditioner.
Cleaning leather seats is a specialty that can take a full day to do.
I’m not a leather cleaning specialist I stayed at a Holiday Inn last night