In college I worked for a leather store (Gepetto’s) near campus. When somone came in with a ‘quality’ leather garment to have cleaned, the owner would take over.
Mark would take it for two or three weeks. First, he would clean it with alcohol, and rub it down till the rag came away clean. Then to ‘recondition’ he used Lexol, a very light coating with a sheepskin scrap. Several times, the lighter the coating, the better.