There are seven basic types of oils in use today. One of these is refrigeration oils which has a function to__________.

• A. to operate in both high and low temperatures
• B. to lubricate at room temperature only
• C. to resist corrosion only
• D. to act as a solvent only

Answer: (A)

Refrigeration oil must keep the moving parts of the compressor protected across the entire operating range of the system. In a refrigeration cycle, the compressor can run hot, raising oil temperature, while the evaporator side can be very cold, lowering oil temperature. The oil needs to stay viscous enough to form a protective film at high temperatures and flow readily at low temperatures so it can circulate back to the compressor. This wide temperature performance ensures reliable lubrication, wear protection, and proper oil return throughout the cycle. Oils that only lubricate at room temperature or that mainly serve as solvents or corrosion resistants don’t meet these demands, so the essential function is to operate effectively in both high and low temperatures.