What Is the Purpose of Motor Oil?

by David Arnold
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A car's engine is the "heart" of the vehicle and needs to be maintained with the proper amounts of motor oil. The purpose of motor oil is to lubricate, clean, protect, cool and sometimes restore engine performance.


When a car is started, engine parts including the pistons create friction in the motor. As the car's speed is elevated, the pistons work harder to pump oil throughout the motor. Motor oil creates a slippery coating of lubrication so that the moving parts can move more fluidly. Without the oil's lubrication, the friction in the moving parts of the motor is greatly compromised and the compression is decreased, resulting in the inability to reach optimal levels of speed and performance.


The coating of lubrication that oil provides also protects the engine. For example, imagine placing two pieces of moving metal against each other. Over time, without lubrication, the metal will begin to wear away. This is how an engine will perform without motor oil. Motor oil protects the engine's moving parts from coming in contact with each other.


Motor oil cleans the engine of debris. As the oil is pumped throughout the engine, the oil collects debris as it travels. The debris is then collected inside of the oil and dispensed into the oil filter of the car. This process keeps the engine clean from debris and material that accumulates from normal use.


Contrary to common belief, antifreeze is not responsible for the entire car's cooling mechanism; the antifreeze in your radiator cools only the upper portion of the engine. Friction in the engine's moving parts creates heat. Motor oil is responsible for cooling the friction that is created in the car's lower portions, including the crankshaft, timing gears, pistons, rod bearings and camshaft, according to the Motor Oil Evaluator website. Without motor oil's cooling capability, the engine will be susceptible to frequent overheating.

Restore Performance

Some motor oils are responsible for engine restoration. Special motor oil blends like that of synthetic and high-mileage oils are formulated to restore the function of the engine. Over time, high mileage can cause an engine to perform less than satisfactorily. These motor oils are used to restore the engine back to its normal factory state, providing increased compression and performance.

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