• SkillCat Team

Types of Refrigerant Oils

Updated: 2 days ago

EPA 608 Core Chapter 2 (Take full course for free)


In this module, we will discuss the different types of refrigerant oils and their applications in HVAC systems. Skip to quiz!


1. Mineral Oils


There are two main types of refrigerant oils:

  • Mineral Oils, and

  • Synthetic Oils


Mineral oils (MO) were first derived from petroleum refining processes. They are produced as a by-product when crude oil is distilled to produce gasoline.


Mineral oil was primarily used with the older generation of refrigerants, including CFCs and HCFCs.


2. Synthetic Oils



Mineral oils were great for the earlier generations of refrigeration systems with CFCs and HCFCs. As the industry phased out CFCs and HCFCs, it had to develop new oils to use with newer refrigerants.


These new oils are called synthetic oils. Synthetic oils are produced from processed petroleum in order to contain specific properties to work with new refrigerants.


Synthetic oils are required while making retrofits because mineral oils are not miscible with modern refrigerants. This means that mineral oils do not mix well with new refrigerants, which prevents refrigerants from doing their job.


Synthetic oils include:

  • Alkylbenzene (AB)

  • Polyolester (POE)

  • Polyalkylene Glycol - (PAG)

  • Polyvinyl Ether (PVE)

Each of these synthetic oils are used with different refrigerants.

Recall that an oil needs to be miscible with a refrigerant in order for the oil to work in a system containing that refrigerant. For example, let’s say an oil is used in a system with HCFC refrigerant. That means the oil has to be miscible with HCFC refrigerant.


Alkylbenzene (AB) is a synthetic oil used in refrigerant systems with CFC or HCFC refrigerants. As we discussed previously, CFCs and HCFCs have been phased out. But HCFCs are still used in blends.


So, for blends containing HCFCs, we need to use alkylbenzene (AB) to service the system.


Polyolester (POE) is a synthetic oil used in refrigeration systems that contain HFC and HFO refrigerants. These oils are also called ester oils.


This means that if a system is retrofitted with HFC refrigerant or HFC refrigerant blends, we need to use polyolester oil. Recall that retrofitting means to modify a system to use a new refrigerant.


Polyolester oils, or ester-b

ased oils, cannot be mixed with any other oils. This is something technicians have to keep in mind when servicing equipment using ester-based oils.


Polyalkylene Glycol (PAG) is a synthetic oil that is used mainly in car air conditioning systems.


And lastly, polyvinyl ether (PVE) is a synthetic oil that is an alternative to POE oils.



3. Conclusion


In this module, we discussed the different types of oils and their applications.


Question #1: Alkylbenzene (AB) oil is used for systems with which of the following refrigerants? (Select all that apply)

  1. CFC

  2. HCFC

  3. HCFC blends

  4. HFC

Scroll down for the answer...


Alkylbenzene is used with systems that contain HCFCs. This includes systems that contain blends with HCFCs.


Question #2 Alkylbenzene (AB) oil is miscible in HCFC refrigerant.

  1. True

  2. False

Scroll down for the answer...













Alkylbenzene is used with systems that contain HCFCs. This means it has to be miscible with HCFC refrigerants.


Question #3 If we are retrofitting a system to use R-134a, which oil do we need to use?

  1. Alkylbenzene (AB)

  2. Polyolester (POE)

  3. Mineral Oil (MO)

  4. None of these. Retrofitting does not require oil use.

Scroll down for the answer...













We need to use polyolester oil (POE) with all HFC refrigerant applications. Since R-134a is an HFC refrigerant, we need to use POE.


Question #4 Polyolester oils are great because they can mix with a lot of other oils.

  1. True

  2. False

Scroll down for the answer...













This is false. Polyolester oils cannot be mixed with any other oils.


Question #5 R-1234yf is not miscible in any refrigerant oils.

  1. True

  2. False

Scroll down for the answer...













This is false. R-1234yf is an HFO refrigerant. HFO refrigerants can be used with POE oils, meaning that HFOs are miscible with POE oils. So R-1234yf is miscible in POE oils.



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