Which is better - oiled or oilless shop or worksite air compressors? You can get either readily, but which type is the best investment?
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You can buy both oilless and oil-lubricated compressors for the worksite and shop. I’ve had an oilless unit for over 5 years and recently replaced it with an oiled version after weighing the price point and life of the equipment.
Oilless units use plastic and low-friction coatings to reduce friction and association wear on moving parts. They tend to run at higher speeds, directly off the motor shaft. They are entirely dependent on air movement for cooling. Because the components that form the air pump on an oilless unit are not entirely encased in the pump, they typically generate more sound (noise) when they are running than an oil-lubricated unit will.
The larger the unit for average shop applications, the more likely the compressor will have an oil-lubricated air pump. That’s fine with me!
I like the fact that I can change the oil as needed, that the pump runs at a lower RPM, is quieter and lower-pitched than an oilless unit, the pump is more durable and runs at lower operating temperatures than its oilless counterpart.
Why the lower operating temperature? There are 3 reasons:
Lower RPM. There is a small pulley on the motor shaft and a large combo pulley fan on the air pump shaft. Because the piston or pistons that create air pressure are usually larger than on oilless units, a large amount of air is pressurized in a short time. High RPMs are not needed to get the same results.
Larger Cooling Fan. As mentioned, the air pump pulley is also a sizable air fan that moves a significant amount of air across the heat dissipation fins of the air pump. Lower temps mean longer life. It’s as simple as that.
The oil does a better job of lubrication AND acts as a coolant. Non-detergent compressor oil is very efficient in keeping all the operating surfaces inside the air pump coated and will not as readily mix with water as detergent oil will. Efficient lubrication reduces friction - so less heat. That’s not all though. The oil itself, as it moves around the air pump’s oil sump, cylinder walls, crankshaft, piston connecting arms, etc., also acts as a coolant and transports heat away from the pump’s “hot spots” and dissipates it to cooler areas in the pump.
Overall, the oiled unit is heavier construction, including a cast-iron air pump case and better motor. Our compressor will be set up as a stationary unit, and we are enhancing the unit further by installing a higher capacity air filter, a valved drain line for the air pump oil (to make oil changes easier and cleaner), and an air tank drain valve extension to make it ultra-easy to drain condensate out of the air tank every few days of operation.
You can see those enhancements by visiting this link:
COMING SOON!
With all that the oiled compressors have going for them, they are my first choice for our shop compressor.
Just Do It Yourself!