More often than not, air compressors require lubrication systems to operate sufficiently and avoid mass amounts of maintenance. Oil tends to be used as lubrication, and it primarily helps to reduce the friction between the components in the pump of the air compressor. This in turn will produce less heat from the friction, consume less energy and provide a longer machine cycle life.
It must be noted, that air compressors are also available oilless… (or Oil-Free) this does not imply that they don’t require lubrication, but instead, they are pre-lubricated and do not need user maintenance to sustain and change the oil inside the compressor. Visit our Oilless Air Compressors vs. Oil Compressors guide for more information!
If you’re wondering how to choose the right kind of compressor oil for your air compressor, which is the best compressor oil, or any other frequently asked questions about air compressor oil – then this ultimate guide to air compressor oil has you covered!
What Kind of Oil Goes in an Air Compressor?
A very common mistake made by a lot of people is that all oils are the same. There is an oil specifically made for air compressors, and it is a certain type that is referred to quite simply as, air compressor oil. They are dubbed ideal, due to being formulated for industrial uses and not having any significant differences in the cost compared to regular motor oil.
It’s very important to follow any guidelines relating to using air compressor oil provided by the manufacturer of your air compressor.
What is Air Compressor Oil?
Air compressor oil has specific additives to make it perfect for the duty cycle it sees inside your air compressor. In contrast to conventional motor oil, which is more commonplace, air compressor oil doesn’t contain a detergent and typically has lower levels of sulfur (sulfur) and carbon.
Carbon and sulfur content are ultimately measured as a percentage by weight – but can also sometimes be referred to as a ratio on the bottle. Air compressor oils can also sometimes be labeled as “low sulfur” or “low sulfur” depending on which part of the world you’re in.
Air compressor oil vs motor oil
Air compressor oil is specially formulated for use within air compressor pumps. Unlike motor oil or engine oil, air compressor oil doesn’t contain many additives used to clean, restore and preserve the inside of an engine. Motor oils are designed to operate in lower temperatures and greater volumes. Compressor oils on the other hand, when produced go through several processes, such as;solvent extracting , desalting, and evaporation – all designed to make them robust and effective at high temperatures.
How to Choose an Air Compressor Oil?
This rule to follow about what compressor oil to use is simple. If your air compressor is under warranty, then you should use the oil that is recommended by the manufacturer and usually noted in the compressor manual/guidebook. If the warranty period for the air compressor has ended, then you could buy suitable compressor lubricating oil from a hardware store to use in your compressor.
Note, this rule should only apply to home DIY compressors. Some of the more sophisticated and larger compressors – rotary screw, reciprocating, etc. – that are used by industry, have very specific requirements for oil. You must use the oil recommended by that compressor manufacturer or you void the warranty or can even cause oil-related issues. These issues will result in significant maintenance costs which are completely avoidable.
Which is Better, Synthetic or Mineral Oil?
When it comes to synthetic vs standard mineral air compressor oil, the choice is very much driven by your duty cycle – how frequently and continuously you use your air compressor.
Air compressor oil lubrication can be made using either synthetic or mineral oil bases. Mineral oil-based tends to be the standard oil for air compressors. Synthetic oil undergoes a significant amount of processing.
When making a decision on which one to use, it can take some careful consideration. Both mineral and synthetic oil are both very suitable for air compressors so the type of work you intend to do with your air compressor and the amount of use must be analyzed.
It can be recommended that if you do not continuously use your air compressor then a standard mineral oil lubricant can be best suited to you. This is because they’re perfect for light to medium-duty air compressor operations. Most importantly, these oils are cheaper than synthetic blends.
If you’re continuously using your air compressor in an industrial setting, synthetic blends can be the better choice due to their more regular use. It is said by multiple users that air compressors run a lot smoother and quieter on synthetic oil lubrication. Not only this, but synthetic oil has an overall greater temperature range and stronger protection against the air compressor overheating.
Summary: Synthetic Oil vs Standard Compressor Oil
| Duty Cycle | Mineral Oil | Synthetic Oil |
| Light Duty / Infrequent Use | Best | ok |
| Heavy Duty / Continuous Use | ok | Best |
Alternative Oils For Air Compressors (Using a Substitute Oil)
Potential alternative compressor oils include:
- ATF – Transmission Fluid
- Engine / Motor Oil
- Hydraulic Oil / Hydraulic Fluid
Does Every Air Compressor Need Oil?
All air compressors are mechanical machines that need oil at some point.
“What about oil-less air compressors?” I hear you say…
Oilless air compressors aren’t actually completely oil-free or devoid of oil. Essentially the term oilless refers to the fact that the compressor doesn’t need to have its oil changed or topped up. In fact, oilless air compressors come “factory sealed” so that the original lubrication cannot be replenished.x
Over time, oilless air compressors lose their lubrication through degradation of their oil coatings and will eventually run out of lubrication, running under high wear – and eventually seizing up.
This is typical of DIY or home-use air compressors which have a light-duty cycle or a highly infrequent duty cycle – such as a car tire compressor that gets pulled out maybe once every 3 months over the course of its life.
So if you have an air compressor at home and you’re wondering whether you should be topping it up with oil, check the user manual! It may well be a factory-sealed unit that doesn’t require you to change or top up the oil.
Most reasonably duty cycle compressors (including many DIY home-use air compressors) do require you as a compressor owner to monitor oil levels and top up the oil based on a usage cycle.
Best Oils for Air Compressors
Numerous oils compete at the top for some of the best on the market, here we will look at a few of those best. To give you a better idea of what you’re looking for. It is, however, recommended to follow your air compressor manufacturer’s guidelines.
Air Compressor Oil Properties & Characteristics
There is a whole range of properties of compressor oil that we could go into, but I’ll cover off the 3 that are of main concern when selecting a compressor oil:
- Operating Temperature Range
- Additives
- Viscosity
Operating Temperature Range
Oils, of any kind, not just compressor oils suffer from oxidation and denaturing due to heat. As heat increases, so does the rate of oxidation and the oil loses its intended lubricating and protecting properties.
Extreme temperatures such as below freezing or above 100-120 Degrees Fahrenheit will often require specialist oils. Equally, your compressor manufacture will have advised the normal operating temperature of the surroundings for your compressor in the user manual.
Obviously, your compressor also generates heat, so the temperature range for the operation of the air compressor stated by the manufacturer won’t also be applicable to the oil itself – which will have to endure much hotter temperatures inside your compressor than the ambient surroundings.
It’s best to consult your user manual – however, you may not find a specific compressor oil temperature range stated. In the event, you’re left scratching your head, wondering whether the compressor oil you have will do the job – don’t panic.
The majority of Air Compressor Oils are designed to work well within typical operating temperature ranges for oiled air compressors. If in doubt, consult your local workshop equipment dealer for reassurance on a specific oil.
Additives
Oil additives are sacrificial chemical elements that impart properties onto the oil that the underlying oil simply doesn’t have the capability to deliver.
For example, motor oils tend to have a detergent content which helps to prevent a build-up of carbon deposits – and prevent the carburized oil from being deposited in the first place!
Air Compressor Oils tend to have more concentration of additives that act as preservatives to prevent corrosion and rusting inside the compressor. Additional lubrication, or “anti-wear additives” can be present in a range of air compressor oils, even some mid-range compressor oil.
Anti-oxidation additives are some of the most important, especially with compressor oil seeing reasonably high temperatures under continuous use. This anti-oxidation additive helps to slow the rate of oxidation and denaturing of the oil.
All of these additives are sacrificial. So over time, these additives lose their potency within the oil, and essentially the oil returns to its “pre-additive” state, but also with a bunch of oxidation thrown in! This is why it’s REALLY important to change oils, even when oil levels “look ok”.
It’s also another reason why completely CHANGING the oil is important, rather than just continuously topping up the compressor oil – leaving the aged, degraded oil to mix with the fresh – additive rich compressor oil.
Viscosity
With the advent of modern oils, viscosity levels have tended both towards the nominal SAE 20 -30 range, meanwhile, the more extreme viscosity level oils are still available, they’re less commonly used in machinery in general.
It’s no different with air compressor oil. A SAE20 or SAE30 oil is perfectly suited for use in an air compressor.
There isn’t actually a huge difference between SAE20 or SAE30 for air compressors – certainly not one that would mean you MUST use one or the other.
Fundamentally, SAE20 is slightly less viscous, meaning at colder temperatures the oil will cause less drag on the compressor and it’ll run slightly more efficiently.
With SAE30 air compressor oil, the viscosity (thickness) is a little higher (more viscous) so at colder temperatures, the viscosity might be a little higher than desired – meaning the compressor would run slightly less efficiently using SAE30 at colder ambient temperatures.
It’s worth bearing in mind that as the compressor runs, the heat generated in operation will reduce the viscosity of both SAE20 and SAE30 compressor oils. Under sustained use in a lower temperature environment, SAE 20 oil will outperform SAE 30 in terms of efficiency.
Under sustained use, in a higher or moderate temperature environment, SAE 30 oil will retain more of its lubricating properties than SAE 20 compressor oil. Meaning the SAE 20 compressor oil will have sub-optimal viscosity (it will go thinner) at a lower operating temperature than SAE 30 compressor oil.
This is an important distinction, but probably only one that will make a significant (noticeable) difference to compressor users who are operating their compressor daily or continuously.
How Often Should you Change Air Compressor Oil?
The answer to this question is unfortunately not as straightforward as you may wish. The answer will vary depending on the size of the air compressor in use or even the type. The time after which the oil needs to be changed will vary significantly from air compressor to air compressor. The best place to gain an understanding of this regularity will be inside your air compressor manual provided by the manufacturer.
Though this is generally recommended, a few little tips can be provided to give you a better scope:
- Change the oil every 3 months on a reciprocating air compressor
- Change the oil between every 1000 to 2000 service/operating hours on a rotary screw compressor
How to change air compressor oil:
- Switch off your air compressor and unplug it
- Let the air compressor cool down
- Drain the air compressor of any oil that remains inside
- Refill with the required amount of oil
How To Check Oil Level on an Air Compressor?
Much like a car engine, some air compressors provide a dip-stick that has an oil level marker/indications on the stick to help you check whether the compressor oil is running low.
However, it’s quite common to find a clear portion or “sight glass” on the side of the oil reservoir or motor mechanism. Some compressors even have a completely clear reservoir for high visibility from a distance.
Once again, markings and indicators are typically provided on these sight glasses. At a minimum, some user manuals might simply say that the oil level must be visible in the small sight glass “porthole”.
It’s important to remember that oil expands under heat! So if the user manual indicates that the oil levels should be measured when the compressor is cold / before the operation – make sure to follow these guidelines! Your compressor could be showing a perfect oil level when hot, but as the whole system cools you could find the oil level is actually below the desired level.
FAQs (Frequently Asked Questions)
What is the Difference between Air Compressor Oil and Motor Oil?
Well, it’s sort of in the name, compressor oil is specifically created for air compressors and motor oil is specifically created for motors. Compressor oil is a non-detergent oil. It’s important to use a compressor oil to comply with the guidelines provided by your air compressor manufacturer.
Motor oil most commonly contains all sorts of detergents, which as you may know, are very beneficial for the internal combustion engine. It, however, can be very harmful to the air compressor though, causing a greater amount of carbon build-up in a shorter time.
If you were to use a different oil like motor oil, this may change your warranty void as mentioned, taking away any advantages of the warranty.What Viscosity Air Compressor Oil Should I Use?
Viscosity refers to the texture and/or consistency of the air compressor oil. Most manufacturers will tend to recommend SAE20 or SAE30. SAE20 is more suited to colder areas, and SAE30 is more suited to warmer temperatures due to its greater viscosity.
Viscosity is a very important characteristic to analyze. Damage to your air compressor may occur if the consistency of your oil is either too thick or thin. Not only damage but work will be delayed.
What’s the best oil to use in air compressors?
This completely depends on your duty cycle, but ultimately we’d advise a high-quality synthetic oil will a high density of preservative, anti-corrosion additives.
How much oil does an air compressor need?
Typically a couple of fluid ounces of compressor oil will do the trick. If you find yourself emptying an entire bottle of compressor oil, you may well have a leak! That being said, the amount of oil that goes in your compressor is highly dependent on the compressor size. Larger compressors typically take more oil as their mechanical pumps are greater in size and ultimately volume.
What oil should I use in my air compressor?
You may use synthetic or mineral oil in your air compressor and have it operate perfectly. You should avoid oils with a detergent additive, these are common in motor oils. So specify a non-detergent oil. In terms of viscosity, you’ll want an SAE 30 or SAE 20 air compressor oil. An ISO 100 oil like this one from AMSOILis typical.
Do air compressors need oil?
Not all air compressors need oil no! All compressors do however require a method of lubrication to moderate heat, friction, and the wear-down of the pump and critical components. Some compressors are specifically oil-free or oil-less, therefore their lubrication comes from a special material coating rather than using oil.
What type of oil do air compressors use?
Typically air compressors will use synthetic or mineral oils, and should preferably be non-detergent. In terms of the viscosity of the oil, it should be around SAE20 or SAE30. Typically your air compressor manufacturer will inform you of what oil should be used with each compressor model. If you can’t find locate your user’s manual where the information will be, you should contact the manufacturer directly.
How do I top up the oil in my air compressor?
Time needed: 5 minutes.
To change the oil in your air compressor follow these steps:
- Switch off the air compressorEnsure the air compressor is switched off, disconnected from the elecrtical supply and cool
- Empty the oilUndo the drain plug (sump plug) and let the oil drain into an empty container
- Refill with fresh ooilReplace the drain plug and top up with your fresh compressor oil
What is an oil air compressor?
Like a reciprocating engine, an air compressor uses a moving piston inside a cylinder to draw in air and then compress it. Instead of igniting the air with fuel and spark, the compressed air is sent into your air tank, where it’s held at high pressure.
All that moving around of the piston inside the cylinder causes a lot of heat and friction. That leads to wear and tear on the item, which isn’t good. Eventually, the piston seals will wear down, and the cylinder will make less air pressure than it was designed to do.
The best way to solve the problem is with lubricating oil. This is precisely like having oil in your car, and for the same reason. It reduces heat and friction. When heat is built up, the oil wicks away from the pump case and the cylinder.
Only by ensuring that the proper amount of oil gets into the cylinder and piston will the pump operate the way it should. The main difference between oilless and oil air compressor units is this oil lubrication and the need to make sure that it is there. It also means that the operator will need to change it occasionally, which means more maintenance.
From:About air compressor.