🔍 Key Concepts

• Behavior of lubricating oil at low temperatures in refrigeration systems • Meaning of viscosity, pour point, and wax content in oils • Why oil must circulate and not solidify or thicken excessively in cold parts of the system

💭 Think About

• Think about what happens to very thick (high viscosity) oil when it is exposed to the extremely cold conditions inside a refrigeration system. Does that help oil flow, or restrict it? • Consider the effect of wax in oil at low temperatures. What would wax do as temperature drops inside evaporators and lines? • Ask yourself whether a high pour point (the temperature at which oil stops flowing) is desirable in a system that routinely operates at very low temperatures.

✅ Before You Answer

• Make sure you understand that pour point should be appropriate for the lowest operating temperature of the system • Check whether wax content should be high or low for good low‑temperature flow properties • Verify if very high viscosity is generally good or bad for lubrication and circulation at low temperatures