AC Compressor Oil Types Explained

Lawrence Bonk Profile image

Written by:

Updated May 18, 2023

If you are new to the world of indoor cooling appliances, you may wonder what kind of oil is best for an air conditioner. The best air conditioners, after all, include powerful motors with various components, some of which could use lubrication or fuel. The main types of AC compressor oil are mineral oil, POE oil, and PAG oil. Mineral oil is for older AC systems, while POE oil works well with newer ones. PAG oil is mostly used in cars. Just like different oil types, there are also multiple home AC refrigerant types that your unit may use.

Keep reading to find out more about these oils.


  • Some air conditioning systems require lubrication to aid with general operation heat dispersal.
  • HVAC system compressors often require specialized oils, such as polyalkylene glycol, at regular intervals to avoid compressor failure.
  • Consult the instructions that accompanied your central air conditioner for information as to when and how to apply this type of oil.

What Oil is Used for Air Conditioners?

Wondering what types of AC motors are used in air conditioners? There is a wide variety, and some require regular lubrication with specialized oils, and the same is true if you are learning what is the compressor of an air conditioner. Of these many air compressor oil types, synthetic lubricants are highly recommended as they provide superior wear protection compared to traditional oil-based equivalents. As a matter of fact, HVAC compressors often require an HVAC compressor oil type to disperse heat and to aid in lubrication, which is the case even if you understand air conditioner voltage. However, the most common type of oil used in an AC unit is polyalkylene glycol, which is a synthetic oil.

Insider Tip

In addition to adding oil to the compressor when necessary, make sure you clean or replace the air conditioner filter.

Beyond compressors, some motors also require specialized oil or lubricant. Without regular maintenance, air conditioning systems break down and stagnate, leading some to wonder what to do when there is mold in your air conditioner. Proper maintenance may also help to prevent you from having to wonder why your AC compressor is not turning on, and you may need to learn how to fix an AC compressor. In fact, good maintenance can decrease the chances of damage to key components, as well as premature wear and tear.

Tips for Proper AC Lubrication

There are some tips to help you make sure your AC system is properly lubricated so it can perform its very best for years to come.

Check the Instructions

While it is true that many compressors attached to HVAC systems require specialized oil for lubrication, this does not apply to all systems. In other words, consult the instructions for information as to how often to apply oil, which oil to apply, and how to apply it. If you no longer have access to a paper copy of these instructions, perform a simple web search to find a relevant PDF or another form of digital document.

Talk to a Professional

If you have had no luck with the instructions or just feel wary of tackling such a task all on your own, reach out to an HVAC pro to pick their brain about the process. This is not their first rodeo, so they’ll be able to tell you exactly how to apply oil to the compressor and when to do it. As a bonus, you can even schedule a service call and let them do it once while you watch, so you’ll know for next time. Of course, service calls cost money, so do so at your discretion.

STAT: The compressor in your HVAC system contains internal parts that move rapidly. This requires a special type of oil for lubrication for smooth operation. The oil also seals the compressor connections to prevent a leak. (source)


How to check the oil level in your HVAC system?

Each system is different regarding how to check the oil level. Consult the instructions for a detailed step-by-step guide on all aspects of compressor lubrication.

How to lubricate a central air fan motor?

Use a specialized type of motor oil to apply lubricant to the condenser coils, condenser unit, and motor fans. Do so at regular intervals but only after learning the correct procedure.

How does a room air conditioner work?

A room air conditioner pulls in hot air from outside, cools it via evaporator coils, and then spits out cool air back into the room.

Lawrence Bonk Profile image