Oil-Lubricated Vs Oil-Free Air Compressors

There is often confusion regarding oil-lubricated versus oil-less air compressors. With air compressor technology changing every year, many homeowners and professionals are left wondering what is outdated and what remains true. 

This guide explores the oil vs. oil-free debate, focusing on reciprocating single-stage air compressors, which are the most common types used in standard 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 of the pump and critical components. The biggest difference is whether the lubrication comes from oil or a special material coating. 

Oil-Free Lubrication 

Oil-less 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 exactly as the name suggests. These compressors use rotating dippers—similar to 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 to Choose? 

Comparing oil and oil-free air compressors is less about which is superior and more about which is better for a specific application. 

• Oil-lubricated air compressors are ideal for most non-sensitive applications. For powering mechanical tools in a garage or on the road, an oil compressor serves well. In fact, most mechanical air tools require a small amount of lubrication to work optimally. 
• Oil-less air compressors are designed for delicate applications where there is a risk of getting oil into the final product. For example, dentists use oil-free compressors to power their air tools so patients do not receive a mouthful of fossil fuel. Paint shops, breweries, and food processing facilities are other areas where oil-free operation is critical. 

Note: Breathing apparatuses require specific types of air compressors that are not carried by Ferguson. 

Although application is the main factor that dictates the type of air compressor needed, there are other basic differences to consider: 

Oil-Lubricated Air Compressors 

• Oil stays in the air 
• More maintenance required 
• Higher airflow models are available 
• Louder performance on average 
• Great for non-sensitive applications (mechanical tools) 

Oil-Free Air Compressors 

• Cleaner, dryer air 
• Less maintenance required 
• Less airflow on average 
• Quieter performance on average 
• Necessary for sensitive applications (paint tools, medical equipment) 

H2: How to Pick One Over the Other 

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

The first two columns compare two portable compressors that are exactly the same except one is oil and one is oil-less. Similarly, the last two columns compare two stationary compressors that are exactly the same except for lubrication. This provides a clear idea of the differences between oil and oil-less models, all else being equal. 

Oil vs Oil-Free: Common Myths 

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

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 oil-free 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 is important to reiterate that the decision between oil and oil-free air compressors must come down to the application and what a user is 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, an oil-less model is the better choice. If the quality of the air does not matter, either type will suffice.