Most people know it is bad to use your vehicle on underfilled motor oil condition. Still, there is tendency to find out how low that is still 'safe' to use the vehicle in underfilled condition.
In contrast, curiousity also arouse: what if we overfilled the engine.
Underfilled: Bad
Not enough lubrication and circulation of heat.
Overfilled: also Bad
Why? The engine will have to work extra 'hypertension' to distribute oil 'our blood' to the whole engine, the engine will feels heavier and generate extra heat. Another factor you must avoid is theoverfilled engine will caused foaming. The submerged crackase stir oil in the engine and caused foaming (volatile with alot of air bubbles) within the oil, thus the engine will be distributing air bubbles instead of oil. (For human: air bubbles in blood vessel is fatal).
Remember to use the engines if only you they are filled with at least 25% above the dipstick!