When shopping for an air compressor, one of the biggest decisions you’ll be confronted with is whether to go with an oil-lubricated or oil-free compressor. Many of the old-school gearheads on website forums will swear by oil-lubed compressors for all sorts of reasons, but there are plenty of advantages to today’s oil-free compressors. In this article, I’ll lay out the key reasons why oil-free may be the way to go for your new compressor.
A Word On Compressor Types
It should be noted that I’ll mainly be discussing air compressors intended primarily for light-to-moderate use around the house, in the workshop, or on job sites. Most large industrial air compressors are oil-lubricated by necessity, so I’ll stick with the smaller, more common compressors.
I’ll also use the most common pump configuration (reciprocating piston style) as the primary example, though many of the same principles apply to other types of pumps.
How Oil-Free Compressors Work
Before we begin, it’s important to understand the basics of how oil-free compressors work in contrast with oil-lubed compressors.
With a basic reciprocating air compressor pump, the pump consists of a cylindrical housing with a piston inside it. As the motor runs and the crankshaft turns, the piston moves up and down the cylinder. With one stroke, the piston draws air into the cylinder through an inlet valve, then compresses it and pushes it into the air storage tank with the next stroke.
In an oil-lubricated compressor, oil is splashed onto the crankshaft, piston arm, and cylinder walls as the piston reciprocates, lubricating the moving parts. In an oil-free compressor, all of the moving parts within the pump cylinder are self-lubricated – that is, they are coated with Teflon or a similar material that minimizes friction and allows for smooth operation.
Now that we have a basic idea of how oil-free compressors work, let’s look at their advantages.
1. Less Maintenance
The first advantage of oil-free air compressors is that they require very little maintenance compared to oil-lubed compressors. The oil in an oil-lubed compressor gets dirty and breaks down over time and needs to be replaced regularly. The oil level also needs to be checked routinely, and oil filters that prevent oil vapor from contaminating the air supply need to be replaced.
With oil-free compressors, there is no oil to be changed or topped off and no oil filters to be replaced.
2. Lower Operational Costs
The cost of oil changes and oil filter replacements can add up over time, so oil-free compressors have an advantage in terms of lower upkeep expenses. The only part that will need to be replaced regularly on an oil-free compressor is the air intake filter.
3. Greater Portability
When it comes time to move your compressor from one place to another, oil-free compressors have a distinct advantage. When an oil-lubricated air compressor is tipped over or put on its side, the oil in the sump can flow into places it’s not supposed to be. Any grit that has sunk to the bottom of the sump will also get stirred up and get on the crankshaft and other moving parts.
Of course, you can drain the oil completely before you transport it – but this isn’t exactly practical if you tend to carry your compressor around between job sites.
With an oil-free compressor, this isn’t an issue – though you should always make sure the storage tank has been completely drained of any condensate before tipping it or putting it on its side.
4. Better Cold Weather Performance
Like most liquids, air compressor oil tends to get a little thicker or have higher viscosity at cold temperatures. This can make it more difficult for the compressor pump to get started, as the oil will be “sludgy” or won’t flow as easily. Some compressors can be operated using low-viscosity or multi-viscosity oil to help counteract this, but this isn’t the case for all models.
Naturally, an oil-free compressor will have generally have no problem starting up in the cold since it contains no liquid that can thicken. If you live in an extremely cold climate and tend to use your compressor outside of a climate-controlled environment, this can make all the difference.
5. Cleaner Air Supply
Air quality is another consideration with air compressors that often gets overlooked.
With an oil-lubed air compressor, a small amount of oil vapor can get past the piston seal and into the air chamber. These compressors are equipped with downstream oil filters or air/oil separators to help prevent contaminated air from entering the storage tank, and some even feature filters downstream from the tank. But these measures aren’t guaranteed to prevent 100% of oil contamination, particularly if the filter isn’t changed often enough.
This is an especially important concern if the compressor is being used in a food-processing setting or for breathing air (scuba tanks, air-supplied respirators, etc.) – but oil can also interfere with pneumatic tools or effect paint finishes, among other things. The best way to ensure that no oil whatsoever is in your air supply is to go with an oil-free compressor.
6. More Energy Efficient
With the downstream filtration required to prevent oil contamination, oil-lubed air compressors often need to work harder (and draw more power) to provide the necessary CFM (cubic feet per minute). This effect is most pronounced on larger compressors but the principle is the same on smaller household models.
Oil-free air compressors tend to consume less energy since they require no downstream filtration that could result in pressure loss. In addition, motor performance will generally remain consistent, unlike with oil-lubed compressors, whose performance may suffer slightly as the oil gets dirty from use or “sludgy” from cold weather.
7. Less Environmental Impact
Another benefit of oil-free compressors that appeals to many people is that they are more environmentally friendly. Their energy efficiency is one part of this, but the mere fact that they don’t use oil is an even bigger part. No oil means less air pollution (heated oil can produce carbon monoxide and other harmful emissions). But it also means that less oil is being used and disposed of, which reduces consumption and minimizes the risk of accidental oil contamination.
Our Oil-Free Air Compressor Recommendation
Now that we’ve covered the benefits of oil-free air compressors, here’s one that we recommend based on our research. We’ve landed on this one after looking at a variety of factors including customer reviews, versatility, brand reputation, and overall value for the price.
This 6-Gallon Oil-Free Craftsman Air Compressor is a perfect option for general use around the house, in the garage, or on job sites.
At a modest 32.5 lbs. and with a convenient carrying handle, this compressor is highly portable and easy to transport in virtually any vehicle. Its compact pancake design makes for easy storage and utility in nearly any setting.
With a 120V, 0.8 HP motor, this compressor can pack quite a punch without draining a lot of power. Boasting an output of 2.6 CFM @ 90 PSI, this compressor makes up for its relatively small tank with rapid recovery times, so you can keep working without having to wait for constant refills.
This powerful output capability, combined with the max pressure of 150 PSI, makes this compressor ideal for a wide range of applications and air tools. It even features dual couplers so you can connect two hoses at one time. To top it all off, it comes with a 13-piece accessory kit that includes a 25-foot hose, blower tools, inflation nozzles, and a pressure gauge.
Best Oil Free Air Compressor
- Oil-free 0.8 HP pump for powerful performance and minimal maintenance
- 150 PSI maximum pressure
- Output rating of 2.6 CFM @ 90 PSI for versatility and rapid recovery
- 78.5 dB noise rating for quieter operation
- Lightweight – 32.5 lbs.
- Compact pancake design and convenient carrying handle for portability and easy storage
- Two quick-connect air hose couplers
- Includes 13-piece accessory suite (25-foot hose, pressure gauge, inflation tools, etc.)
- Made in the USA