when I was 17 and worked at a full service fuel station. myself and another employee were trying to close when a lady came in and bought a qt of oil, she came back in a couple of minutes later and bought another, and another, and another. I asked her what she was doing and she replied. "My husband told me to check the oil, and its really low. All this oil and its no where near filling up that little hole."
We pushed her car onto a rack and drained almost three gallons of oil.
Then we showed her how to check her oil.