What is the different between oil-free air compressor and oil-lubricated air compressor?

The difference is the oil content in compressed air.

• For the Class 0 oil-free air compressor, we use water as the lubricating medium instead of oil, so there will be no oil at all.
• For the oil-lubricated air compressor, we use oil as the lubricating medium, so the compressed air will contain oil. But the use of filters can reduce the oil content down to 0.003 microns.