How to Safely Switch to an Aftermarket Oil

To ensure your new aftermarket oil is a true match for your compressor, follow these three steps:

1. Cross-Reference the OEM Specification Never guess based on color or viscosity alone. Look at your compressor’s manual or the OEM oil bucket. Provide the exact OEM part number (e.g., Sullube 32, Ultra Coolant, QuinSyn) to your aftermarket supplier. A reputable supplier will have an exact chemical crossover chart.

2. Perform a Compatibility Test If you are unsure what oil is currently in your machine, take a sample of the old oil and a sample of the new aftermarket oil. Mix them 50/50 in a clear glass jar, shake vigorously, and let it sit for a few days. If the mixture turns cloudy, separates into layers, or forms sediment, do not mix them in your compressor.

3. When in Doubt, Flush it Out If you are transitioning from a PAG oil to a PAO, or if you simply do not know what was previously in the machine, you must perform a system flush.

• Drain the old oil completely (including the oil cooler, lines, and air/oil separator).

• Fill the system with a dedicated compressor flush fluid or a baseline PAO oil.

• Run the compressor lightly for the recommended time to circulate the cleaner.

• Drain the flush fluid, change the oil filter and separator, and fill with your new aftermarket oil.

The Base Oil Compatibility Matrix

If you are “topping off” your compressor with an aftermarket equivalent without doing a full system flush, understanding compatibility is vital. Below is a quick reference guide:

Important Note: Even when two base oils are marked as “Compatible,” mixing brands means you are mixing different additive packages. Additive clashes can reduce the lifespan of the oil. A complete drain and flush is always the best practice.