Question: When a compressor has unloaders, why is the oil viscosity important, especially in regard to internal vs. external unloading?

- Frank Smith, Greater Chicago Chapter

Answer: All Copeland compressors use the same 150 viscosity lubricant. No other viscosity is recommended whether the compressor is a version that incorporates unloaders or is a non-unloading model. The unloading used on all but one Copelamatic compressor is of the blocked suction or Moduload variety. All of those are the internal style. The only exception is the 9R model line, which uses the external bypass method.

-Wesley Taylor Jr., service training specialist Copeland Corp.