Q: What might cause the engine oil level to be low without any leakage?

Hi. The most common cause of this problem is worn internal engine components. The engine’s valve seals could be leaking oil into the engine. The engine would then burn the oil, causing oil consumption without any external oil leaks. Worn-out piston rings could cause this as well. You can try using oil additives designed to slow engine oil consumption to help with this problem, or you can use a thicker oil in the engine. Higher mileage vehicles tend to burn 1 to 2 quarts of oil every 1000 to 1500 miles; this problem is not uncommon for high-mileage engines. If you’d like to enlist some professional help with this issue, you can always contact a certified technician, such as one from YourMechanic, to diagnose and repair your oil consumption problem for you.