What happens if you drive with a car that has no oil in it

First you need to know the need for engine oil, its main function is to lubricate the frictional surfaces of the engine. secondly, it plays a main role in flushing out the impurities(due to different burning conditions) form the cylinder walls and other engine parts. Thirdly, extract and dissipate minor amount of heat from the cylinder walls.

Now, assume there is no oil in your car, It won’t drive far at all ,most likely will lock and spin the bearings on the connecting rods and same with the crankshaft main bearings as all these bearings are not a ball bearing, but actually a strip of flat very soft metals layered together totaled about a sixteenth of inch thick and are sandwiched between the surface of the rotating assembly of the crankshaft and engine block.

The connecting rods and crankshaft are completely dependant upon the engines oil pumped under pressure through galleys, that position the continual oil supply to the center of those bearing strips and act as a cushion and lubricate the spinning rotating assembly as the engine runs.

Without that continual oil supply under pressure, when the two metal surfaces come into direct contact, it will cause immediate friction and heat that breaks down the soft metal strips of metal (bearings). The metals melts and causes it to fall out of the area it is placed and then you will hear a loud knocking sound from the motor. That will fatigue the connecting rod and it will snap under the load of the engine running and spinning at such a high rate of speed when it snaps it will often punch a whole in the side of the engine block that houses it and that is the catastrophic failure that will stop the engine and render it completely destroyed and unrepairable.

This is the worse case scenario and will usually take about from five minutes run time to possibly an hour at most dependant upon many factors before catastrophic failure happens no oil in the motor and this is absolutely to happen.

In summary,

A car with no engine oil in it will have no lubrication of mechanical contact areas, results in excessive heat thereby damage of major parts.

The impurities remain on the cylinder walls resulting in cracks and grooves on the cylinder and piston results in poor performance.

No heat dissipation.