Refrigeration lubricants serve a critical function beyond simple lubrication. They reduce friction in compressor bearings, seal internal clearances, remove heat from moving parts, and must remain miscible with the refrigerant throughout the entire system temperature range. The two dominant lubricant chemistries in refrigeration today are polyol ester (POE) oil and naphthenic mineral oil.
POE oil is a synthetic lubricant engineered specifically for use with HFC and HFO refrigerants. Mineral oil is a petroleum-derived lubricant traditionally used with CFC and HCFC refrigerants. Selecting the wrong lubricant type leads to poor oil return, compressor wear, and system failure.
Polyol ester (POE) refrigeration oil is a synthetic lubricant produced by reacting a polyol alcohol with organic acids. POE oils are fully miscible with HFC refrigerants such as R-134a, R-404A, R-407C, R-410A, and R-507A, making them the required lubricant for modern refrigeration systems.
POE oil is mandatory for any system charged with HFC refrigerants (R-134a, R-404A, R-407C, R-410A, R-507A) or HFO refrigerants (R-1234yf, R-1234ze). It is also the recommended lubricant for retrofit projects converting from R-22 (HCFC) to HFC alternatives.
Qishanr QSL series POE oils (QSL-32H, QSL-46H, QSL-68H, QSL-100H, QSL-170H, QSL-220H) are approved for use in scroll, screw, and reciprocating compressors from BITZER, Carrier, Trane, HANBELL, Hitachi, York, Copeland, and Danfoss.
Naphthenic mineral refrigeration oil is refined from specially selec crude oils with naturally low wax content. Mineral oils have been the standard refrigeration lubricant for over 80 years and remain the correct choice for systems using CFC, HCFC, and certain natural refrigerants.
Mineral oil is the correct lubricant for systems using CFC refrigerants (R-12, R-502), HCFC refrigerants (R-22), ammonia (R-717), and hydrocarbon refrigerants (R-290, R-600a). It should not be used with HFC refrigerants due to immiscibility.
Qishanr GS series mineral oils (3GS, 4GS, 5GS) are recommended by major equipment manufacturers for commercial and residential refrigeration and air conditioning systems.
| Property | POE Oil (e.g., QSL-68H) | Mineral Oil (e.g., 3GS) |
|---|---|---|
| Chemistry | Synthetic polyol ester | Naphthenic petroleum |
| HFC Compatibility | Fully miscible | Immiscible (not compatible) |
| HCFC Compatibility (R-22) | Compatible | Fully miscible |
| Natural Refrigerants (R-290, R-717) | Limited compatibility | Compatible |
| Thermal Stability | Excellent (flash point 280°C) | Good (flash point 168°C) |
| Moisture Sensitivity | High (hygroscopic, requires sealed handling) | Low |
| Viscosity Range | ISO VG22 to VG220 | ISO VG32 to VG56 |
| Pour Point | -25°C to -40°C | -40°C to -50°C |
| Cost | Higher | Lower |
| Shelf Life | Shorter (moisture absorption) | Longer |
| Typical Applications | HFC/HFO systems, R-22 retrofits | R-22 systems, CFC systems, ammonia, HC |
The primary factor in selecting between POE oil and mineral oil is refrigerant type. The lubricant must be miscible with the refrigerant to ensure proper oil return to the compressor.
POE oil is hygroscopic, meaning it absorbs moisture from the atmosphere. Exposure to air degrades POE oil and can introduce acid formation in the refrigeration system. Always store POE oil in sealed containers, minimize exposure time during charging, and use a vacuum pump to remove moisture before charging.
Mineral oil is not hygroscopic and tolerates brief air exposure without significant degradation. However, contamination with water, dirt, or incompatible oils must still be avoided.
Mixing POE oil and mineral oil is not recommended. While they are technically miscible with each other, a mixture reduces the miscibility of POE oil with HFC refrigerants. During R-22 to HFC retrofits, the system should be flushed to remove at least 95% of the original mineral oil before charging with POE oil.
R-410A is an HFC refrigerant blend that is completely immiscible with mineral oil. If mineral oil is used in an R-410A system, the oil will not return to the compressor, leading to oil logging in the evaporator, reduced heat transfer, and eventual compressor failure from oil starvation.
Yes. POE oil is compatible with R-22 and can be used as a direct replacement for mineral oil in R-22 systems. This is commonly done as a preparatory step before retrofitting to an HFC refrigerant. However, there is no performance benefit to switching from mineral oil to POE oil if the system will remain on R-22.
Refrigeration oil in a properly maintained sealed system does not require routine changes. Oil should be replaced when the system is opened for major repairs, when acid levels exceed acceptable limits (acid number > 0.05 mg KOH/g), or when retrofitting to a different refrigerant type.
Always follow the compressor manufacturer's specification.es are ISO VG32 for small reciprocating compressors, ISO VG46 for medium-duty applications, and ISO VG68 for screw compressors and high-load conditions. Higher viscosity grades (VG100, VG170, VG220) are used for large industrial screw and centrifugal compressors.
Qishanr offers both POE and mineral refrigeration oils to cover every application:
All Qishanr refrigeration lubricants are available in 1L, 4L, 5L, 18.9L, 20L, and 200L packaging. Contact us for technical support and bulk pricing.
