Most everyone has heard the saying: “oil and water do not mix. If you have to clean up a grease or oil stain from leather, do not use water. It will only make the stain worse. First, blot the excess grease or oil from the leather. Sprinkle cornstarch over the stain and let it sit overnight. The following day take a soft cloth and wipe the cornstarch away. The cornstarch should have lifted the grease or oil stain.