Air compressor oil is a synthetic form of lubrication that coats moving internal parts, preventing friction and overheating of core motor components. Many air compressors use a combustion engine motor to pressurize incoming air; this air powers items as varied as nail guns and paint sprayers. Lack of oil will damage the machine, possibly requiring a motor rebuild or replacement.
A basic air compressor uses moving pistons within a cylinder. As the pistons move up and down within the cylinder, air is forced into the compressor. Air continues to accumulate within the compressor's tank, causing the molecules to become more dense and compact. A tool, such as an air drill, will receive this pressurized air through a hose connected to it from the compressor. The air forced into the tool creates kinetic energy for the device to function.
The air compressor oil plays an important part within the piston and cylinder assembly. The piston moves rapidly through the cylinder, generating friction and heat. Oil lubricates the cylinder, allowing the piston to move seamlessly without any physical damage. Over time, the oil may need to be replaced to retain the best motor action for the compressor.
Most air compressor manufacturers suggest using synthetic compressor oil, instead of conventional oils. Synthetic oil types have the benefit of offering similarly sized molecules through manufacturing processes, compared to the naturally mixed molecule sizes of conventional oil. As a result, the synthetic oil lasts longer and lubricates better than conventional oil. Additionally, synthetic air compressor oil does not have any contaminants within the droplets that can contribute to excess friction and piston damage.
Each air compressor has a different oil viscosity that is recommended by the manufacturer. Consumers should follow the individual compressor owner's manual to verify the correct oil type. Air compressor oil that is too thick for the internal parts will build up and impede part movement. On the other hand, excessively thin oil will provide no coating for moving parts, possibly causing damage to the pistons and cylinders.
Consumers should also note that air compressor oil contributes to an overall quieter machine. Air compressors are notoriously known for being loud; the oil helps muffle the noise by allowing parts to move against each other in a less abrasive manner. Some air compressors are advertised as oil free types. The resulting noise from these compressors tends to be much more distracting than the oiled compressor types, however.