Understanding A/C Compressor PAG Oil Application Charts

Cooling System

By Rodney (Mechanics)

To keep your car’s AC working right, use the right oil for the compressor. Most cars from 1996 onwards need PAG oil with R134a refrigerant. Using the wrong oil type or thickness can mess up the compressor and make it fail. Stick to the right oil to avoid problems with your AC compressor.

Sometimes, PAO (Polyalphaolefin) oil can be used instead of certain PAG oils, but only if the compressor maker gives the thumbs up.

CAUTION: Never ever use PAG oils in hybrid cars because they conduct electricity. Hybrid vehicles with electrically-driven AC compressors usually need POE (polyol ester) oil because it doesn’t conduct electricity. Using the wrong oil could let electricity flow back through the AC compressor, which is super dangerous.

Mineral oil is only suitable for older R-12 AC compressors because R-12 doesn’t mix with R-134 refrigerant.

Be cautious with “universal” AC compressor oils; they’re often PAO-based and might not have the right thickness as the recommended PAG oil for your specific compressor. This mismatch can cause poor lubrication and make the compressor fail too soon.

In newer cars with R-1234yf AC systems, you need either PAG YF 46 or PAG YF 100 compressor oil, depending on what the compressor needs and what the vehicle maker recommendation.

For General Motors vehicles like the 2013/14 Cadillac XTS and 2013 Cadillac ATS with R1234yf AC systems, GM recommends specific lubricants (PAG-PSD1 #19260643 and PAG-ND12 #19299051). Don’t use universal compressor oils for R-1234yf applications.

Hybrid and Electric Vehicles usually need PAG SP-A2 (ISO 46) oil for their AC compressors. This special type of PAG oil doesn’t conduct electricity, which is important for vehicles with electrically-driven compressors.

PAG Oil Recommendations for Various Compressors

Here’s a list of lubricants recommended by the compressor manufacturer. You can find out who made the compressor by checking for a tag or label on the unit, or by referring to the illustrations on the right and left.

Compressor Model and Recommended PAG Oil

AC Compressor Lubricant Recommendations

A/C Compressor Oil Capacities

When you change a compressor or another part of the A/C system, make sure to refill the compressor oil that’s been lost. Remember, most modern car A/C systems only hold about 4 ounces (120 ml) of oil. Not enough oil can cause the compressor to fail.

Caution: Overfilling the A/C system with compressor oil can degrade its cooling performance, so be sure to add only the necessary amount.

When you’re replacing A/C parts, here’s the recommendation compressor oil to add:

  • Compressor: Add 1.4 oz
  • Condenser: Add 1.0 oz
  • Evaporator: Add 1.5 oz
  • Accumulator: Add 1.0 oz
  • Hoses: Add 1.0 oz

Keep the oil you add for replaced parts below the system’s maximum oil capacity.. For reference, better check the A/C service sticker under the hood or read the manufacturer’s service manual.

It Safe Using Universal A/C Compressor Oils?

Here’s our straightforward advice: Stick with the specific PAG oil recommended for your compressor instead of gambling with a universal oil.

Every compressor maker agrees: The right oil type is key. Usually, it’s a PAG oil.

When an engineer designs an A/C compressor, they establish precise tolerances demanding a specific viscosity, friction profile, and wear additives in the lubricant. If the oil used doesn’t closely match these requirements, it could lead to wear and friction problems. Ultimately, this could result in compressor failure.

PAG 46, PAG 100, and PAG 150 oils, like 5W-20, 5W-30, and 10W40 motor oils, vary in viscosity. Do not mix different viscosities because the resulting mixture may not meet the required viscosity range for the application, for various reasons. Thicker oils are typically designated for heavier bearing and seal loads, necessitating slightly wider bearing clearances. Using a thinner oil might lead to insufficient lubrication. Similarly, an application that calls for a thinner oil to reduce friction and drag may not receive adequate lubrication if a thicker viscosity oil is used.

Due to the differing viscosities of various PAG oils, crafting a universal oil formulation mirroring the exact viscosity of PAG 46, PAG 100, or PAG 150 is nearly impossible. Such a universal blend would end up being a compromise, unable to meet any of the original equipment manufacturer (OEM) specifications. It would be too thick for some applications and too thin for others.

Using a universal oil might be fine for some compressors, but it’s risky for others. Since A/C compressors are expensive, it’s not worth the gamble.

Universal oils are popular because they simplify inventory for stores and shops, allowing them to carry just one oil type rather than several.