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What Happens To An Engine Without Oil?

Date: 11/13/2017

Everyone knows that an engine is designed to operate with oil. It’s common sense, the law of the land, if you will. Oil acts as a lubricant for the engine while it runs, and is a pretty integral part of the machine. But have you ever wondered what actually happens to an engine that runs without it? Luckily, we have the answer.

In order to understand what happens to an engine without oil, here’s the low-down on what happened during an experiment that compares an engine running with oil to an identical one running without oil. Needless to say, don’t try this at home.

To make this a fair experiment, some variables had to remain constant. In this case, this involved using the exact same engine; a 212cc one-cylinder Harbor Freight Engine. Each test occurred 24 hours apart (with oil first, followed by without oil) in order to allow adequate time for the engine to cool. Each experiment therefore began with the engine at the same resting temperature. The oil used was also kept consistent, with a chosen APA certified Premium motor oil from a grocery store. The point of this choice was to demonstrate how integral even the cheapest engine oil can be in an engine’s functionality and lifespan, particularly when compared with no oil at all.

Five points were monitored on the engine in the experiment including the crankcase at the bottom (where the resting level of the oil sits), the top of the crankcase (where no oil sits), the air cooled cylinder, the exhaust pipe that exits the exhilarator before it enters the muffler, and finally the valve cover (in this case, a push rod style valve with overhead valves).

Given these variables were kept constant throughout this experiment, any extra heat from the engine without oil can be concluded as a result of the lack of oil, which when present acts as a lubricant to keep the engine cool and clean. During the experiment, ambient air temperature was about 15 to 16 degrees Celsius. Prior to the experiment, the engine was stored in a garage away from direct sunlight and outdoor conditions, which resulted in a cooler temperature before beginning.

While you would expect the temperatures of the engine without oil to exceed those of the one with, about eight minutes into the experiment this wasn’t the case. It was interesting to see that the temperatures of the engine without oil actually remained slightly cooler than the engine without, when measured from the outside. The only exception was the exhaust, which was slightly higher in temperature in the oil-less engine than the one that was lubricated. So does that mean if you want your engine to run cool, you should remove the oil? This is definitely not the case, as seen once the engine was opened up.

At the conclusion of the experiment, pulling apart the engine revealed that running it without oil for a mere 15 minutes actually caused some quite severe internal damage. A dark metal-infused oil (minimal left over that hadn’t quite fully drained from the first experiment) remained inside the engine after running without oil, compared with a clear, clean oil from the first run with it. The creation of this negative sludge, which is then distributed throughout the engine as it runs, only does further damage to areas of the engine where the clean oil would normally act positively.

Further examination of the integral parts of the engine such as the connecting rod cap from the crank shaft and the crank shaft itself also demonstrated signs of permanent damage. This is a result of the metals rubbing and churning against one another without the oil to help them slide smoothly, preventing scratches and reducing the likelihood of any damage.

The experiment concludes what we already know to be true - while an engine is able to run for a while without oil, eventually it will combust. In some cases, this will be much more extreme than in this experiment. Bigger engines will likely begin smoking, burst into flames and/or explode if they run without oil for too long. So basically, don’t go driving around in a vehicle with an engine that is lacking in oil. At least now you know exactly what will happen if the oil isn’t regularly checked and changed and why it is so important to ensure your engine is properly lubricated before running it.