An air compressor is a heavy-duty tool that can be hooked to many different air-powered tools. There are plenty of brands that specialize in all different sizes of air compressors from portable to heavy duty, but the main difference between an oil and-oil free compressor is that an oil-based compressor requires constant attention to the level and quality of its oil. Oil-free compressors still use oil, but they are set once bought. In other words you never have to deal with its oil for the span of its lifetime.
An oil-based compressor will be larger in size than an oil-free compressor. This adds power but requires more upkeep with the oil it uses. If you are going to move the compressor around a lot and take it places you will want an oil-free compressor for its smaller, more portable size. If you are going to leave it in one area and bring your other tools to it, then the oil-based compressor is more ideal.
Since oil-based compressors are larger and more powerful, they are more expensive. The price range will be $600 to $1,200 if you are shopping online or at your local hardware store. Oil-free compressors can be much cheaper; you can get one online for as little as $200. Their range is $200 to $900.
Type of job
For projects around the house, oil-free is more ideal for its size. An oil-free compressor can comfortably run two nail guns at the same time. The oil-based compressor, however, is more likely to be used in a large factory or construction site. It can keep many more tools running for a much longer period of time.
Oil-free compressors break down more often and don't last as long as a bigger cast iron oil-based air compressor. Oil-free compressors are lighter and don't have as much metal to protect them should something hit it, or a part wear down. Oil-based have extra metal protection since they are usually made of iron and heavier metals that shield them more from harm.
No matter what compressor is bought, it is going to use a good amount of power to keep its air pressure constant. Size determines how many amps it will take to keep it running efficiently. The amount of power it needs also brings into question the other tools around the compressor, such as if it is powered by an extension cord. For bigger oil-based models that need more power, you need to increase the size of the extension cord to run all that power. Oil-free compressors should be fine with regular extension cables.