See Related: Best Air Compressors
No, you should not put motor oil in your air compressor.
Automotive motor oil contains additives that make it potentially harmful to your air compressor.
That said, a lot of us are doing it.
If you can find your owner’s manual, it will likely recommend using a non-detergent 30-weight oil.
However, many folks have anecdotal evidence of running their compressor on 5w, 10w, 20w and 30w motor oils (Mobil 1 is a favourite).
And they’re probably right…
But just because you can, that doesn’t mean that you should.
In the following article, we’ll go over everything there is to know about motor oil and air compressors and why you shouldn’t ever use regular motor oil in your compressor, even though you can.
What Happens If You Put Motor Oil In An Air Compressor?
Essentially, different types of oils have different properties, making them ideal for lubricating the insides of specific machines.
When you use the wrong type of oil in an air compressor, it will likely cause unexpected behaviour, potentially destroying the compressor.
For starters, most motor oils contain detergents.
When these are agitated by the movement of your compressor, they will likely foam up, which will prevent them from adequately lubricating the machine’s pistons.
At high temperatures, this can also cause a build-up of carbon inside your compressor, which, over time, will impede the motor’s power and capacity.
That said, both regular motor oil and oils that are specifically designed for air compressors have different optimal working temperatures and viscosity.
Therefore, even if the motor oil doesn’t damage your compressor, it will prevent it from working at its optimal performance level.
What Kind Of Oil To Use In Air Compressor?
Whether you purchase your oil online via Amazon or physically going to the store, you need to make sure that you’re buying the correct type of oil for your specific application.
Your air compressor’s user manual will be the best guide when it comes to telling you what type of oil you should be using to lubricate its insides.
However, typically a non-detergent or inorganic oil is going to be best.
If you’re unable to find your user’s manual or can’t find the recommended oil, typically, using either a 20w or 30w oil will be adequate. These oils are most commonly used in air compressors and aren’t likely to cause any damage.
It’s also recommended that you use an oil with a wear-reducing agent, such as Monolec, which will create a molecular film over the surface of the air compressor’s inner working and will help keep them lubricated at all times.
Air Compressor Oil Vs Motor Oil
The most significant difference between air compressor oils and motor oils is that:
- Motor Oils Have Detergents
- Motor Oils Have Emulsifiers
- Motor Oils Are Formulated For Higher Heat
- Motor Oils often contain more ash
In other words, the difference between air compressor oil and motor oil is the additives.
These detergents and emulsifiers are excellent for removing carbon build-up and carrying that engine crud to the oil filter.
An air compressor doesn’t have a filter. So the motor oil simply carries the crud around inside the compressor.
The theory is that these abrasions can harm the compressor over time.
Because of this, you will see compressor manufacturers insist that you use non-detergent oils in their machines.
The emulsifiers inside the oil also mean that water tends to become trapped inside of the oil. This can lower the effectiveness of lubrication.
Additionally, conventional motor oil contains a lot of ash. These ash residues can get deposited on the valves, and this carbon build-up can reduce the effectiveness.
Some synthetic oils also contain a high-ash. It is only the best, full-synthetic oils that get away from this ash problem. Mobil 1 and Chevron have some of the lower-ash oils on the market.
Viscosity and how hot your compressor gets is the next essential item. Many folks use 5w-30 or 10w-30 in their compressors. The thing is, these oils don’t thicken to a higher weight unless they get hot enough.
A too-thin oil may not provide adequate protection. Additionally, it can seep past the piston rings and enter the air tank.
Because of this, it is vital to use a single-weight oil that has the proper viscosity.
That said, many folks swear by 5w-30 and 0w-30 synthetic oil for their compressors — especially in cold climates where hard starting is a problem.
See Related: 5w-30 in a compressor.
Lubrication is critical. It prevents wear and overheating. It is better to use engine oil than it is to use no oil. The damage that might occur is likely to only happen after years of use. And enough folks have been using motor oil in their compressors for decades to make me think it isn’t a problem — unless a warranty is involved.
I’d even argue that clean motor oil is better than dirty air compressor oil.
Viscosity
Different oils have different viscosities or pour points. Essentially, viscosity refers to the oil’s thickness at specific temperatures.
Generally, an SAE 30 (ISO 100) oil is the right thickness for your air compressor.
As alluded to before, colder weather sometimes calls for lighter-weight oil, whereas you can occasionally use heavier-weight oils during warmer weather.
Regardless, it’s highly recommended only to use the type of oil as advised by the manufacturer.
How Often To Change Your Compressor Oil
Like the motor oil in your car, the length of time you can go between oil changes genuinely depends on how often you use your air compressor.
Most compressors should have their oil changed every six months for mechanics or those who use their compressor almost every day.
However, if you are only a weekend warrior or only use your air compressor once in a blue moon, you can get away with only changing the oil once a year.
In reality, your air compressor’s manufacturer should provide you with specific instructions on how often you’ll need to replace your oil.
While it’s easy to say that using your air tools and compressor more often means you should change the oil more often, specific instructions are usually provided by working hours.
In other words, the manufacturer might recommend changing your oil every 100 working hours, for example.
That said, synthetic oils often have longer lifespans and won’t need to be changed as often as conventional oils.
However, the most important thing is to regularly check your compressor’s oil level via the sight glass or dipstick.
By allowing it to go low on oil or oil-less, it will heat up and prematurely wear away at the compressor’s inner components.
Why We Don’t Want Detergents in Compressor Oil
As we’ve already mentioned, you should never use oils that contain detergents in your oil compressor.
These detergents are primarily designed for car and truck engines. Their job, essentially, is to break down and remove any carbon deposits, oxidation, or corrosion that may be building up inside your engine. The detergents help remove these, which are then filtered out by the engine’s oil filter.
However, air compressors don’t usually have oil filters, which means that, although the detergents will break down and remove any carbon deposits, it won’t have anywhere to go, and it will simply float around in the oil.
There’s also another reason you don’t want to use oils containing detergents in your air compressor.
Typically, air compressors that have a lower-delivery piston use a process called splash lubrication.
This means that when the piston moves into the lower position, oil splashes onto it, allowing it to lubricate itself while the engine is running continually.
When you use conventional motor oil containing detergents, this can cause the lubricant to foam up, which will reduce the motor’s splash lubrication. Essentially, the liquid oil will now need to “splash up” through the foam to lubricate the crank, leading to less lubrication per rotation.
In turn, this can cause your air compressor motor to wear prematurely and overheat, which will ultimately reduce the compressor’s lifespan.
There are, however, some modern high-end motor oils with detergents that will also contain anti-foaming agents. This will work better than regular motor oil, but it’s still not recommended.
In other words, stick with what your manufacturer tells you.
Or, if you can’t get the recommended oil, it’s best to only use non-detergent motor oil or low-foaming oils in your compressors.
In the end, NEVER use hydraulic oils, mineral oils, or oils with detergent in your air compressor.
Functions Of Oil In Air Compressor
Whether you’re talking about the combustion engine in your car, or the combustion engine in your brand new Campbell Hausfeld air compressor, the reason for oil is primarily to lubricate the pistons and keep things moving smoothly.
Your air compressor pump has many moving parts inside it, and oil helps keep them lubricated and protects them from corrosion and premature wear.
Furthermore, because the compressor’s piston and interior parts are made from metal, they gradually build heat the more prolonged the machine is running. Therefore, on top of lubricating these parts, oil also helps to keep them cool.
Additionally, because a combustion engine needs to be sealed airtight, oil also helps seal the smalls openings and cracks, enabling it to maintain the pressure needed to function correctly.
Finally, the oil in a well-lubricated air compressor has one other purpose: to help keep the insides clean.
The air filter does an excellent job of capturing most contaminants. However, some smaller nanoparticles will still make their way through and will get caught in the oil.
That’s why, when you changed either your vehicle’s motor oil or your air compressor’s oil, the oil will be considerably darker and blacker than it was when you first put it in.
Rotary Compressor Lubrication
Rotary compressors or screw compressors work by forcing gas into a smaller space by a rotating screw, vane, or lobe.
However, unlike reciprocating compressors, rotary compressors are a different beast.
They need synthetic ISO 68 oil and are less forgiving than reciprocating air compressors.
They are also less forgiving if filled with the wrong fluid.
When this type of compressor works normally, it can impact the lubricant, causing a severe decline in viscosity or causing excess evaporation, oxidation or carbon deposits.
In the end, it’s always important to follow the manufacturer’s directions on what types of oils to use.
By doing so, not only will you ensure optimal performance, but you’ll also help extend the life of your beloved air compressor!
Zachary Drumm
Hey! My name is Zachary Drumm! This site allows me to test new tools, piddle around in the garage, and share the insights I get from flipping cars and houses. When it comes to tools, home improvement, and being a “shade tree mechanic,” you’ve come to the right spot. If I’m not in the garage creating content, you’ll find me outside, running, canoeing, and traveling. My goal is to empower more people to be self-sufficient.