Shiny stools like oil may be related to indigestion, upper gastrointestinal bleeding and so on. 1. Indigestion: If you consume too much greasy food in your diet, and due to indigestion, the grease is excreted directly from the body, it will lead to shiny stools like oil, and you should pay attention to a light diet in general. 2. Upper gastrointestinal bleeding: common in peptic ulcer, acute erosive gastritis bleeding, etc., resulting in a small amount of bleeding in the digestive tract, the blood stays in the stomach for a longer period of time, which leads to tarry stools, so that the stool is shiny like oil. At this point, you should seek medical attention to avoid delaying your condition. If the shiny stools look like oil persistently without relief, you should consult a doctor in time to clarify the cause of the disease under the guidance of a medical professional.