Which lubricant was traditionally used in R-12 CFC refrigeration systems?
Substitute refrigerants and oils · EPA 608 Core. The correct answer, and the reasoning behind it.
Why there are no true drop-in replacements, and fractionation in blends.
The question
Which lubricant was traditionally used in R-12 CFC refrigeration systems?
- Silicone oil
- Polyolester oil
- Polyalkylene glycol oil
- Mineral oilCorrect answer
Why “Mineral oil” is correct
CFC systems such as those using R-12 traditionally used mineral oil. Many substitute refrigerants, including HFCs, do not mix with mineral oil, which is why retrofits often require an oil change.
Source: EPA: Test Topics
Why the other answers are wrong
- Silicone oil — Silicone oil is not used as a refrigeration compressor lubricant.
- Polyolester oil — Polyolester oil is the usual partner for HFCs such as R-134a.
- Polyalkylene glycol oil — PAG oil is used mainly in automotive R-134a systems.
Practice more of this
More EPA 608 Core practice questions, or see every EPA 608 practice test.
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.