Air Supply UK: Specialist Compressed Air Engineers

Published: 07/05/2024

How to add oil to your air compressor: a step-by-step guide

Air compressors contain many moving parts, and oil-lubricated compressors require specialist oil to keep these moving parts lubricated and reduce unnecessary wear and tear. You’ll need to regularly check and replace the oil to ensure your machine runs smoothly and performs efficiently.  

In this blog, we’ll cover everything you need to know about adding oil to your compressor, including:

  • What is air compressor oil?
  • How to check the oil in an air compressor
  • How to fill air compressor oil in 4 simple steps
  • How often should you change compressor oil?

What is air compressor oil?

Air compressor oil is a lubricant designed specifically for compressors. It should not be confused with motor oil, which typically contains detergents and additives that can harm compressors.  

For more information about compressor oil and its benefits, see our blog, ‘What oil to use for an air compressor?’.  

How to check the oil in an air compressor

You should check the oil level of your compressor regularly. If you don’t check and replace the compressor oil, you’ll likely notice a decrease in your compressor’s performance and a drop in the quality of your compressed air. 

Checking the oil level is fairly straightforward. Compressors have a special oil window where you can check how much oil is left in them. This window is usually located on both sides of the compressor. 

Make sure that the compressor is on a flat surface before you check the oil.  Ideally, the oil level should be around the halfway mark. It’s time to change the oil if it’s significantly below this. You shouldn’t start your compressor if the machine has too little (or too much) oil.

How to fill air compressor oil in 4 simple steps

Compressor oil is added through the oil cap on the top of the compressor. Here are the 4 simple steps you’ll need to follow:

  1. Remove the fill cap on the compressor. 
  2. Drain all the old oil inside the compressor using the drain plug. 
  3. Add oil through the compressor cover using a funnel. 
  4. Check the oil level through the oil sight glass or window. If you haven’t added enough oil, add some more. If you’ve added too much oil, use the drain valve to drain some. Having too much oil in your compressor means there’s a risk that the excess oil will leak out of the compressor or affect the quality of the compressed air. 

How often should you change compressor oil?

If you don’t change your compressor’s oil, your machine will start to sound extremely noisy because of the increased friction between the moving parts. 

Depending on how often you use the compressor, you’ll need to change it every 3 to 12 months. Compressor oil’s useful life is 12 months, so even if you don’t use your compressor at all, you’ll need to replace the oil annually. 

How Air Supply can help

If your compressor is louder than usual or isn’t performing as it should, even after you’ve replaced the oil, there could be another problem. Our experienced technicians offer comprehensive diagnostics and repair services for all makes and models of compressors and compressed air systems. We also offer compressor maintenance and servicing to increase your machine’s lifespan and reduce the likelihood of frequent repairs. 

Air Supply also offers a wide range of used and new air compressors at competitive prices and used machines available for hire. So you can rely on our team for all your compressed air needs. 

Contact us today to learn more about our products and services, or speak to a team member if you have any questions about adding oil to your compressor. 


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