In the world of air compressors, choosing between oil-free and oil-lubricated models can be confusing and daunting.

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Both types have unique benefits and limitations and making the right choice will depend on your industry or specific application needs and requirements.

This blog will help you understand the critical differences between oil-free and oil-injected air compressors and provide you with the information you need to make an informed decision.

Whether you're a professional mechanic or a manufacturing plant manager, this article will give you a better understanding of the pros and cons of each type and help you determine which one is right for your industry application. 

Are Oil or Oil-Free Air Compressors Better?

Oil-Lubricated Vs Oil-Free Air Compressors

There's often confusion about oil-lubricated versus oilless air compressors. 

With air compressor technology changing every year, many homeowners and professionals are left wondering what's outdated and what's still true.

So, let's get to the bottom of the oil vs. oil-free debate. For the sake of simplicity, we'll focus on reciprocating single-stage air compressors, since those are the most common types found in common applications.

 

 

Oil vs. Oil-Free: How Air Compressors are Lubricated

All compressors, regardless of their type, need lubrication to moderate heat, friction, and the wear down of the pump and critical components. The biggest difference, however, is whether the lube comes from oil or a special material coating.

 

Oil-Free Lubrication

Oilless compressors do not use oil for lubrication. Instead, their wearable parts are coated in special friction-reducing chemicals and designed to be self-lubricating for the compressor's lifetime.

 

Oil (Splash) Lubrication

Splash lubrication is the most common type used in reciprocating single-stage air compressors. It works just how it sounds. These compressors use rotating dippers (think of small flat spoons) attached to the bottom of connecting rods that swing and splash oil up from the reservoir against the internal moving parts.

 

 

Which Type Should I Get?

Comparing oil- and oil-free air compressors isn't so much about which is better as which is better for your application.

Oil air compressors are great for most non-sensitive applications. If you need to power mechanical tools in a garage or on the road, an oil compressor will serve you nicely. In fact, most mechanical air tools need a little bit of lubrication to work optimally.

Oilless air compressors are designed for delicate applications where you can't risk getting oil into the final product. For example, dentists use oil-free compressors to power their air tools so their patients don't get a mouthful of fossil fuel. Paint shops, breweries, and food processing facilities are other applications where oil-free operation is critical. 

[NOTE] Breathing apparatuses require specific types of air compressors that are not carried by Air Compressors Direct.

Although application is the main factor that dictates the type of air compressor you'll need, there are some other basic differences between oil and oil-free air compressors that are summarized in the table below. 

Oil-Lubricated Air Compressors

Oil-Free Air Compressors

Oil stays in the air

Cleaner, dryer air

More maintenance required

Less maintenance required

Higher airflow models available

Less airflow on average

Louder performance on average

Quieter performance on average

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Great for non-sensitive applications (mechanical tools)

Necessary for sensitive applications (paint tools, medical equipment)

 

How to Pick One Over the Other

It's sometimes helpful to compare real-world examples. The table below compares four actual air compressors and their specs.

The first two columns compare two portable compressors that are exactly the same except one is oil and one is oilless. Similarly, the last two columns compare two stationary compressors that are exactly the same except for lubrication. This will give you an idea of the difference between oil and oilless, all else being equal. 

 

Oil vs. Oiless Comparison

20 Gal. Portable

Oil Lubricated

20 Gal. Portable

Oil-Free

60 Gal. Stationary

Oil Lubricated

60 Gal. Stationary

Oil-Free

Weight & Pump Drive Type 200 lbs
Belt Drive 132 lbs
Direct Drive 261 lbs
Belt Drive 213 lbs
Direct Drive Pump Material Cast Iron Aluminum Aluminum
(Cast Iron Sleeve) Aluminum Max PSI 135 PSI 125 PSI 135 PSI 120 PSI Max CFM 5.2 @ 90 PSI 6 @ 90 PSI 12.8 @100 PSI 10.6 @ 90 PSI Noise Rating 80 dBA 53 dBA 85-90dBA 75 dBA

 

Oil vs Oil-Free: Common Myths

As mentioned, there's often significant confusion about oil and oilless air compressors. Here are some myths we've busted.

Myth #1: Oil Lubricated Compressors Last Longer

Although routine maintenance and regular oiling did tend to make oiled compressors more durable in the past, this just isn't true anymore. Today's oilless compressors run cooler and come better protected than ever before.

 

Myth #2: Oil-Free Compressors Are a Lot LOUDER

While oil-free compressors were unquestionably loud in years past, today's designs feature sound-reducing technologies that make oilless compressors quieter, on average, than oil models.

 

Myth #3: Oil-Free Compressors Don't Need Maintenance

Although oil-free compressors don't require oil changes, they still need some light maintenance. This includes replacing the air filter and cleaning/draining the drain valve if it's not automatic. Overall, though, oil-free compressors require less maintenance. 

 

 

The Bottom Line

Ultimately, it's important to reiterate that the decision between oil and oil-free air compressors must come down to application and what you're trying to accomplish.

While the performance differences between these compressors were more pronounced in the past, today, each is designed to do its respective job well. In general, for sensitive air jobs, go with oilless. If the quality of the air doesn't matter, go with either. 

 

 

 

By Melissa C.

Air Compressor Expert

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