Refrigerant and oil compatibility
The chart
| Refrigerant | Family | Oil | We stock |
|---|---|---|---|
| R-22 | HCFC (single) | Mineral | Stocked |
| R-32 | HFC (single) | POE | Stocked |
| R-410A | HFC blend | POE | Stocked |
| R-134a | HFC (single) | POE | Stocked |
| R-404A | HFC blend | POE | Stocked |
| R-407C | HFC blend (zeotropic) | POE | Stocked |
| R-448A | HFO/HFC blend (zeotropic) | POE | Stocked |
| R-23 | HFC (single) | POE | Stocked |
| R-508B | HFC blend (azeotropic) | POE | Stocked |
| R-1234yf | HFO | POE | Stocked |
| R-1234ze | HFO | POE | Stocked |
| R-407A | HFC blend (zeotropic) | POE | — |
| R-407F | HFC blend (zeotropic) | POE | — |
| R-427A | HFC blend | Mineral or POE | — |
| R-438A | HFC blend | Existing mineral/AB/POE | — |
| R-454B | HFO/HFC blend | POE | — |
| R-152a | HFC (single) | POE | — |
| R-125 | HFC (single, blend component) | POE | — |
| R-143a | HFC (single, blend component) | POE | — |
| R-290 | Hydrocarbon (propane) | Mineral | — |
| R-600a | Hydrocarbon (isobutane) | Mineral | — |
| R-123 | HCFC (single) | Mineral | — |
| R-717 | Ammonia (natural) | Mineral | — |
| R-11 | CFC | Mineral | — |
| R-12 | CFC | Mineral | — |
R-427A and R-438A are formulated to tolerate residual mineral oil, which is what makes them retrofit blends. Every other HFC and HFO in the table needs a full POE charge.
Why mineral oil fails with HFCs
Oil leaves the compressor with the discharge gas whether you want it to or not. It travels the whole circuit and has to come back, and it comes back by being carried in the returning refrigerant.
With R-22 and mineral oil, the two are miscible: the oil dissolves in the liquid refrigerant and moves with it. With an HFC, mineral oil is not miscible. It separates, pools in the evaporator where it is coldest, and stays there. The compressor loses oil steadily until a bearing fails.
Polyol ester is synthetic and is miscible with HFCs, which restores oil return. That is the whole reason POE exists in this industry.
What POE costs you in return
POE is strongly hygroscopic. It absorbs moisture from the air far faster than mineral oil, and it holds far more of it. Moisture in a refrigeration circuit hydrolyses the ester into acids, and acid attacks winding insulation and forms sludge.
The practical consequences: keep containers sealed, do not leave a system open longer than necessary, and pull a genuinely deep vacuum before charging. This is why evacuation discipline matters more on POE systems than it ever did on mineral oil ones. See evacuation and moisture.
Retrofit: the residual oil question
Converting an R-22 system to an HFC blend means changing the oil, and the difficulty is that you cannot get all the old oil out. It is in the compressor sump, the accumulator, the oil separator and wetting the walls of every metre of pipe.
Standard practice is repeated drain-and-flush cycles, running the system between changes to circulate the new charge, until residual mineral oil is low enough that oil return works. Manufacturers publish the target for their own products, and it is a small percentage.
This is why R-427A and R-438A exist. Both are formulated to tolerate a meaningful residue of mineral oil, which shortens the flushing work. That tolerance is the main reason to choose them over R-407C, which needs a full POE conversion but matches R-22's capacity more closely. See retrofit options.
Alkylbenzene, and the ones that are neither
Alkylbenzene is a synthetic oil that sits between the two. It is miscible with HCFCs and tolerates some HFC service, and it appears in older commercial systems and in R-438A service.
Hydrocarbons such as R-290 and R-600a are miscible with mineral oil, which is one reason they suit small sealed systems.
Never mix oil types without knowing what is already in the system. An unknown oil mixture is as much of a problem as an unknown refrigerant mixture, and it is harder to diagnose.
Quick answers
Can I use mineral oil with R-410A?
No. Mineral oil is not miscible with HFCs, so it never returns from the evaporator to the compressor. R-410A needs POE.
Why is POE oil a problem for moisture?
It is strongly hygroscopic. It absorbs and holds far more water than mineral oil, and moisture hydrolyses the ester into acids that attack winding insulation.
Do I have to change the oil to retrofit from R-22?
For most HFC blends, yes, to POE. R-427A and R-438A are formulated to tolerate residual mineral oil, which is their main advantage as retrofit blends.
What oil does R-407C use?
POE. It is an HFC blend, so mineral oil will not return properly and a full oil conversion is needed on a retrofit.
- US EPA · retrofit guidance and lubricant compatibility for HCFC replacement · epa.gov.
- AHRI Standard 700 · refrigerant purity and contaminant limits · ahrinet.org.
- ASHRAE Standard 34 · refrigerant designation and blend composition · ashrae.org.
This guide is general information compiled from the cited sources — not legal, safety or engineering advice. Read our full disclaimer.
Related: Mineral oil vs POE explained · R-22 retrofit options · Evacuation and moisture · Compressor burnout