How to Choose the Right Refrigerant Oil

One of the great misconceptions about synthetic refrigerant oils is that they’re all more or less the same. In fact, there are big differences among them in solubility, viscosity, and additives. 

Oil isn’t a one-size-fits-all commodity. Treat it like a critical component in the system (because it is). Follow these best practices to make sure you’re stocking and using the right oil for the job:

1. Sanden Oil for Sanden Compressors

Roughly 70% of our refrigerant oil sales at Red Dot is Sanden SP-15 PAG oil. Sold in 8-ounce metal cans, this is the standard service oil for heavy-duty Sanden compressors in North America. It’s the only oil approved by Sanden—anything else will risk voiding the warranty on a failed compressor.

2. Choose the Proper Viscosity

Viscosity is a measure of the oil’s resistance to flow. It is classified by ISO grade, measured in centistokes (e.g. ISO 46, ISO 100, or ISO 150). The numbers represent the viscosity of the lubricant like 10W-30 or 10W-40 represents the viscosity of engine oil.

Choose a service oil with the ISO grade recommended for the compressor make and model. Ideally, it should be a double end-capped PAG (end-capping is a chemical process that makes PAG polymers more stable and less affected by moisture).

3. Stock a Variety

Maintain a selection of high-quality refrigerant oils, including double end-capped PAG 46, PAG 100, and PAG 150; Sanden SP-15; and POE 68. With a variety of oils on hand, you’ll be able to properly service most heavy-duty A/C compressors.

4. Packaging Matters

Buy oil in smaller containers to better control moisture ingression. At Red Dot, we believe that metal containers and drums work best (metal is not hydro- scopic). As always, keep containers tightly closed when the compressor oil is not being dispensed.

Heavy-duty A/C compressors are generally robust and can handle some abuse. The bad news is when they overheat and fail, they’re expensive to replace. When in doubt, check with the compressor manufacturer to make sure you’re using the proper oil and viscosity rating.