Vanishing Oil - I overheard a person relate that they had recently changed the oil (added 5 quarts of oil) and replaced the filter. Left the car on a flat surface for a day on a clean cement driveway. Came back and there was not a drop of oil left in the oil pan, no oil on the dip stick and no evidence on the cement driveway of any leaks or leaks in the engine bay. Where did the oil go?
Sounds like a Click & Clack Tappet Brothers question. What kind of car? Did a thief drain clean oil at Oil Pan Drain, then replace plug? -Or- Was engine capacity 8-Qts.? How low was engine oil before oil change? If "empty" then your narrator under-filled it by 3-Qt., in which case Dipstick would register clean if the guy was that much of a Dipstick about it.