Technically, the answer is yes. You can pour motor oil into the air compressor. However, the oil used must have a specific composition and properties that make it an excellent alternative to compressor oil. If the engine oil has reached the viscosity and weight of regular compressor oil, that’s okay. When using engine oil with an air compressor, it is recommended to use non-detergent engine oil. Ensure that the weight of the engine oil is 20 or 30. Otherwise, even the compressor will not work and can lead to disasters. One thing to note is that air compressor manufacturers do not recommend the use of motor oil. Therefore, if you have to use motor oil, ensure it is recommended by the product manufacturing company. You may lose a warranty if you use motor oil that has not been recommended by the air compressor manufacturing company.