Fluctuating Viscosity of Refrigeration Oil Is a Quality Red Flag

When your partner is hot and cold, it’s an attitude issue. But if your refrigeration oil’s viscosity keeps swinging up and down, that’s a quality problem.

The grades of refrigeration oil, such as ISO VG32, VG46, VG68 and VG100, refer to its kinematic viscosity measured at 40°C, with the unit mm²/s. The higher the number, the thicker the oil.

Selecting the right viscosity is just like finding a suitable partner — matching matters a lot. For small, high-speed compressors, ISO VG32 or VG46 is recommended. Medium screw compressors normally adopt ISO VG68. Large low-speed compressors and low-temperature operating conditions require ISO VG100.