How Much Oil Does My Air Compressor Need?

Compressors Air compressors

Air compressors require constant oil lubrication to prevent friction on the pistons or screws and other moving parts. To make sure your air compressor is running efficiently, it is important to check your oil level regularly and to know how much oil your compressor needs.

Before adding any oil to your air compressor, you want to check your compressor manual for guidelines on checking/adding oil to your unit. The manual will indicate exactly how much oil you should add into the sump for your model of compressor. Once you have read the manual, you should be able to locate the oil sight glass on your compressor. It may be found on the base of the pump for reciprocating type compressors or on the sump tank in a rotary screw compressor. In the middle of the sight glass, you will see a dot. Ideally, you want the oil level to be in the center of the dot. If the oil level is below the dot, your unit needs more oil. If the oil level is above the dot, you have added too much oil.

Sigh Glass Too Full

This oil sight glass is showing that the oil level is too high.

What Can Happen if I Add Too Much Oil?

We often receive calls from customers saying, “My compressor is spitting oil.” or “There is oil coming out of my compressor lines.”  Those are both indications that the air compressor was overfilled with lubricant.

Typically when we think of adding/changing oil, we think about the oil in automobiles. When oil is added, it is usually filled near the top, which is why there is a common misconception of having the same practice for air compressors. However, filling your compressors oil sump to the top can cause significant internal damage to your unit. When excess amounts of oil become aerosolized by the compressor’s discharge, it can cause damages not only to your compressor, but to any pneumatic tools and accessories that are hooked up to your compressor. Oily discharge can also ruin your end-product, sometimes to the point where projects must be scrapped and reworked entirely. Any spray painting, sanding or the application of finishes would be ruined by oil entering the airstream.

To keep your air compressor running as efficiently as possible, it is important to make sure it is always operating at the proper oil level. With preventative maintenance, you’ll greatly reduce the risk of having projects ruined by the interference of oil in your compressor’s airstream

Have questions about adding the proper amount of oil to your Chicago Pneumatic compressor? Contact us at

CP service technician in fron t of CP compressor

Whether you have questions about which compressor is right for you, or if you’re ready to improve your operations and start saving on expenses. Chicago Pneumatic has been around for over 100 years because we offer reliable and hardworking air compressors, as well as expert advice and support.

Experts' articles

Why a Chicago Pneumatic VSD Expert Corner

Why Is My Compressor Vibrating?

Regardless of the type of compressor you have, vibration issues can be troubling for any business. The root of the vibration can stem from multiple sources, some internally and others externally. Understanding the cause of the vibration and how to resolve them will be critical in keeping your compressor in proper working order.

Can my compressor be outside

How Do I Winterize My Air Compressor?

Regardless of whether or not it actually freezes where you live, most winterization service recommendations are also basic, solid maintenance procedures that will help extend the life and operational efficiencies of air compressors regardless of whether you live in northern Maine or South Florida.

Expert Corner Dryer

Where Should I Install my Air Dryer?

Your company purchased an air dryer for your compressor. One of the most common things we see in the industry are air dryers being stored on top of the compressors. Seems like a wasted space not being used on top of the compressor, right? Wrong.