Two thirds. According to the query of Pacific Auto Network, the oil of the screw air compressor in the Red Fifth Ring Road is increased by two thirds, and the oil of the air compressor needs to be above 0.6 vertical to use the special air compressor oil. The air compressor is the main part of the air source device, which converts the mechanical energy of the prime mover, usually the motor, into gas pressure energy and generates compressed air pressure.