How much oil does my air compressor need? It’s often a straightforward question, but sometimes it is difficult to provide a simple answer. This page is addressed at the DIY air compressor owner and the users of these, relatively low cost, home and small workshop air compressors.
Know that if you have an oil-lubricated compressor, you will need to add oil to the sump from time to time. The normal operation of the compressor pumps allows small amounts of lubricating oil to migrate from the sump, up the cylinder wall, and into the air compression chamber. From there the oil flows into the tank along with the compressed air.
Pumps with bad cylinder seals will allow even more oil to leave the compressor sump.
How Much Oil Does My Air Compressor Need? Not Too Much!
Overfilling the oil sump on a lubricated air compressor can create problems. In fact, it is better to underfill the sump just a bit than overfill it.
The logical first step to finding out how much oil the air compressor needs is to check the manual that came with the air compressor if you still have it. If your air compressor is oil lubricated, the manual will indicate so, and tell you how much oil the sump needs to be full.
The manual will indicate the exact amount of oil your compressor needs. Once you add the recommended amount of oil, find the oil sight glass on the compressor and check to ensure that you can see the oil clearly. More on the oil sight glass below. If at this point you are wondering what type of oil to get for your compressor, the Powermate Px P018-0084SP 100% Full Synthetic Air Compressor Oil, is a cheap, affordable option available on Amazon.
Of more use in checking the compressor oil, since who can find their compressor manual years after we bought the darn thing, is to use either the sight glass or the oil dip stick.
Best Air Compressor Oils
Best Overall: Royal Purple 01513 Synfilm Recip 100 High Performance Synthetic Air Compressor Lubricant – 1 qt.
Best To Cool Down and Quiet Your Compressor: Mobil 101016 Automotive Accessories, 1. gallons
Best To Extend The Life Of Your Compressor: Ingersoll-Rand Ingersoll Rand 32305880 Start-up Kit for Model 2420/2340/2475 Air Compressors
Compressor Oil Level Sight Glass
Once you add oil to your compressor, the next best thing to do is to check the oil level sight glass. The oil sight glass helps to determine the level of oil in the air compressor. Normally, this glass may be found on the sump tank in a rotary screw compressor or on the base of the pump for a reciprocating type compressor.
Look on the side of, and near the base of the pump, which is where the oil sump is located. You may see a sight glass similar to the one in the photo above.
If your air compressor uses a sight glass to help determine the oil level in the sump, examine yours, and see where the oil level is. If the oil level is at the middle of the center dot (it’s a red one on this sight glass) then your oil is at the correct level. An oil level any higher than this would be considered over-filling.
So, ideally, you want the oil level to be in the center of the dot. If you find that the oil level is below the dot, then add more oil. If the oil level is above the dot, you added too much oil.
No sight glass? Then if your air compressor is oil lubricated, it will almost invariably have a dipstick.
Compressor Oil Dipstick
The oil level dipstick is typically part of the oil-fill tube cap.
The oil fill cap inserts into the oil fill tube, typically found near the tip of the oil sump, as can be seen in the following image.
The correct oil fill level should be indicated on the leg of the dipstick.
The dipstick and the cap have a small hole in them to allow the oil sump to breathe. Absence of the hole, or if the hole is plugged, may lead to pressure or vacuum to develop in the sump. If you don’t already have a compressor oil dipstick, you can get this Rolair Oil Dipstick on Amazon.
Other Compressor Oil Dipsticks On Amazon
No Dipstick & No Sight Glass
What if I want to check my air compressor oil level but the compressor doesn’t have a sight glass and aI don’t have a dipstick. If this is the case with your air compressor, you may want to double check to be sure that it actually is a compressor to which you must add lubricating oil. Many modern compressors are built to be self-lubricating, and no external lubrication is needed.
In the event your compressor is – for sure – oil lubed, does not have a sight glass, does not have a dipstick, you have a couple of options.
Take the measurements of your oil sump. Close counts. Take a photo of it from two sides. Take the photo and the dimensions with you to the compressor store. Find a compressor on display with a comparably sized oil sump, find the manual for the new compressor, and note the correct oil level for that compressor, and use that as a guide for yours.
Or, with a handy supply of rags (you will need them) and a large container, pull the sump drain plug (can be seen in the image above) and drain all the oil into the container. Measure the volume. Use an ounce or two more than this volume to refill the oil sump with fresh oil. Cross your fingers!
What If I Added Too Much Oil?
So while there is a risk in adding too little oil and causing friction and overhearing, there is also a risk in adding too much oil to your air compressor. Unlike adding oil to cars, where we normally fill up to the top, doing that is not a good idea for air compressors. One of the main indications that you added too much oil id when customers say:
“My compressor is spitting oil”
“There is oil coming out of my compressor lines”
Both of these issues indicate that the air compressor was overfilled with oil and are just mechanisms to get rid of the excess lubrication.
Filling up your air compressor sump to the top can actually result in serious and significant internal damage to your compressor unit. Why is that?
Well, whenever you fill up the sump with excess amounts of oil, the oil will be come aerosolized, which means it will be converted into a fine spray when the compressor discharges.
This can damage the compressor as well as any related pneumatic tool, accessories and other peripherals attached to the compressor.
Moreover, oil in the compressor discharge can get into the airway and ruin the compressed air coming from the compressor.
Think about it, what if you are pumping your compressed air to atomize white paint but the oil gets into the compressor airstream and into the paint. What a mess! Many projects have had to be scrapped in the past because of issues like this. Another good example is oil getting into the airstream while sanding fine wood.
Why Do Air Compressors Need Oil?
Air compressors are made of many moving parts and require constant lubrication to prevent friction on the pistons or screws as well as all other moving parts.
This is why oil is very important of air compressors because, without it, there will be too much friction which may very well damage certain parts of the compressor.
Proper oil levels is important to keep your air compressor working efficiently and so you should make it a priority to check your oil levels regularly and know how much oil your compressor needs.
Before Adding Oil To Your Air Compressor
As we mentioned before, you should check your air compressor manual for the proper guidelines on adding oil to the compressor unit since different compressor brands and models will require varying amounts of oil.
Remember, to keep your compressor operating at its optimal, you will always need to make sure that it is operating at the proper oil level. This is why preventative maintenance is important.
If your air compressor is low on oil, you can grab the Powermate Px off Amazon, it’s a great, affordable choice.
Air Compressor Oil Change–Extend the Life of your Air Compressor
When Do You Change Your Air Compressor Oil?
Like with many things, the answer is, it depends. Some people only think of changing their compressor oil if the compressor oil becomes black. That’s not a good idea.
If your air compressor is running in a plant environment, one, or two or three shifts a day, you are probably changing the air compressor oil regularly, at about 200 hour intervals of use, or whatever that specific air compressor manual tells you.
But what of those of us at home with workshop air compressors that will not likely see 200 hours of compressor use over a number of years? You are, of course, keeping the oil in the sump to the correct fill level with new oil, as the compressor consumes oil. That is adding fresh oil, depending on how much your air compressor oil gets consumed. Even with that, you do want to change out the oil with a fresh supply once a year as a maximum interval between compressor oil changes.
Oil Is In My Air Compressor Air Line
Norgren, a major manufacturer of compressed air treatment products, reminds us that “coalescing filters do not remove oil that is in the vapor state in the supply air. Vapors are typically removed using an activated carbon filter. Always protect a vapor removal element by removing oil aerosols with a coalescing filter before the vapor removal filter.”
Sounds like good advice to protect the life of the activated carbon filter.