Most leather has some oil in it to begin with, due to the tanning process or conditioning with mink or linseed oil. Also, true leather (particularly suede) has an absorbent quality; if you leave the stain long enough, it will likely disappear on its own. But, of course, an oil stain is unsightly. The best leather treatments are aggressive, expensive and not readily available. First, try the more gentle home methods of stain removal, which will not dull or discolour your leather goods.
Dust the stain and surround area with talcum powder. The powder will absorb oil.
Leave the talcum on the stain overnight.
Brush away the talcum with a suede brush. Most of the oil should have disappeared; if not, repeat the above steps until the stain is removed.
"Iron" the stain with a hot spoon. Boil some water, and dip a large metal soup spoon in the water for 30 seconds.
Lay white tissue over the oil stain.
Rub the hot spoon over the tissue. The heat should help the tissue to absorb the oil.
Moisten a cotton ball with lighter fluid. The fluid evaporates completely, and acts as an organic solvent for oils and grease.
Rub the cotton ball over the stain; as the area is moistened, the stain should become invisible.
Rub the area with a dry cotton ball, while the leather is still damp with lighter fluid. This should absorb any surface oil.
Allow the lighter fluid to evaporate completely. The stain should have disappeared, or should be much less conspicuous.
Repeat the above steps until the stain is completely gone.
Wash the leather with a moisturising facial bar, if the above fails. Ivory and Dove are particularly mild and well-suited to leather.
Moisten a white terrycloth facecloth, or a piece of cheese cloth.
Work up suds on the cloth with the facial bar.
Rub the stain gently with the soapy cloth. Quickly remove the soap with another clean, moistened cloth. The stain should disappear.
Common sources of oil stains on leather are food, hair products, perfumes and colognes. Avoid eating in leather clothing. Apply any perfumes and colognes before putting on the leather goods. Use an antimacassar (a protective cloth) on a leather couch or chair, to absorb hair oil. Use talcum powder, not cornstarch, on suede leather. Talcum is more drying than cornstarch.
Do not smoke when using lighter fluid. Do not soak the leather with soap; try instead to loosen the oil near the surface. Any oil below the surface will be absorbed.