An ideal oil is best at handling only high temperatures and high pressures.

• A. True
• B. False
• C. Not sure
• D. Only high temperatures

Answer: (B)

Lubricants in refrigeration systems must perform across the full operating range, not just at high temperatures and high pressures. An ideal oil needs to lubricate effectively during startup when the system is cold, maintain the right viscosity at elevated temperatures to prevent wear, and be stable and compatible with the refrigerant and system materials throughout cycling. If an oil were only good for high temperature and high pressure, it would likely be too viscous or too thin at other times, fail to circulate properly on startup, or cause oil-refrigerant separation. So the statement is false.