How POE oil differs from mineral oil, and whether the compressor oil must change when an R22 system moves to R407C or another HFC. Residual mineral oil, retrofit routes and a checklist — from Lubrizol and Emkarate documents.
The short answer
- If the system moves to an HFC refrigerant (for example R407C), the oil must become POE, and as much of the old mineral oil as possible must be removed, because mineral oil does not mix with HFC.
- Residual mineral oil can reach about 10% of the charge, according to the Emkarate RL brochure, and can spoil the miscibility of the POE — leading to fouling of the evaporator and falling efficiency.
- Moving to R32 or R410A is more than an oil change — it normally means equipment or a compressor designed for that refrigerant. See our R22 and retrofit guidance.
- Follow the compressor maker for oil type and grade — see how to choose a POE grade.
How POE and mineral oil differ
| Topic | Mineral oil | POE (polyol ester) |
|---|---|---|
| Miscibility with HFC | Not miscible | Designed to mix with HFC |
| Where it is used | Traditional R22 systems (Danfoss's table lists mineral oil for some R22 compressor series) | HFC systems, and some R22 compressors |
| Oil return | With HFC, oil collects in the evaporator | Oil circulates with the refrigerant and returns to the compressor |
| Properties | — | The Emkarate RL brochure states better viscosity index, flash/fire point and pour point than conventional mineral oil |
Lubrizol explains that when oil and refrigerant do not mix well, oil accumulates in the evaporator, starving the compressor of lubrication and lowering system efficiency.
Changing from R22 — route by route
| Moving to | Oil | Note |
|---|---|---|
| R407C (retrofit) | Must become POE | A retrofit route that keeps the compressor, but the oil must change and equipment be adjusted per the manufacturer's documents |
| R32 / R410A | The oil the new equipment's maker specifies (per manufacturer tables, often POE or a model-specific ester) | Usually a replacement of the machine or compressor, not a recharge of the old unit |
| R134a and other HFCs | POE | For systems designed for that refrigerant |
A general summary — confirm the route for each machine with its manufacturer.
Residual mineral oil — why retrofits fail
The Emkarate RL brochure explains that even after the mineral oil is drained and a POE is charged, residual mineral oil can make up as much as 10% of the lubricant charge. It can spoil miscibility, coat the evaporator and cut efficiency to an unacceptable level. The maker therefore advises removing as much mineral oil as possible, following the oil maker's retrofit procedure.
Our refrigerant retrofit page quotes the criteria compressor makers use — do not skip steps: that page notes that systems failing after a retrofit usually do so because steps were skipped, not because the replacement refrigerant cannot be used.
Checklist before changing oil and refrigerant
- Identify the old and the new refrigerant, and confirm the machine's manufacturer allows the route.
- Check the oil grade the compressor maker specifies — see the Emkarate RL grade table by compressor type.
- Plan the removal of the old mineral oil following the oil maker's and compressor maker's procedures.
- Replace the parts the manufacturer's documents require, such as the filter-drier, and check pressure-relief devices.
- Keep the oil container closed until you are ready to charge — compressor makers set a very low water content for the oil.
FAQ
Can POE be mixed with mineral oil? Not recommended — a large residue of mineral oil spoils the miscibility of POE with the refrigerant, so as much as possible must be removed in a retrofit.
Can I charge R32 into an old R22 unit? No — R32 and R22 work at different pressures and with different oils; use equipment designed for R32. See our R22 and R32 pages.
Can Emkarate RL be used for the oil change in a retrofit? The maker states Emkarate RL supports changeovers from CFC and HCFC to HFC systems and is designed for both initial fill and service fill — but the grade must match what the compressor maker specifies.
Ask for advice and a quotation
Planning a retrofit or an oil change? Send the compressor model, the old refrigerant and the new one, and we check the oil grade and quote — see Emkarate RL POE compressor oil. Prices follow grade, size and volume, so none is published on the website.
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