Thanks, The nature of my inquiry is from a customer complaint. I operate a repair shop and was accused of not putting oil back into an engine during an oil change. The customer took the car home, parked it for 2 months then drove about 300 miles. After the trip, the engine had a knocking sound and the customer added 4 quarts of oil to the engine. Since there was no oil present under the car where it was parked, and no oil present under the vehicle from driving 300 miles, she is convinced that we forgot to fill the engine with oil. Most vehicles would show signs of leakage on the chassis from a drip, but I suppose it is possible that the aerodynamics of some vehicles would allow the oil to get “blown” to the ground depending on the air turbulence and body design. The car is a 1968 Mustang.