Unlike most machinery, air compressors are very forgiving when it comes to using alternatives to regular AC oil. Considering how difficult it can be to find and/or afford AC oil, alternatives are important to try to ease both issues.
But, are air compressor oil substitutes reliable? The common AC oil substitutes are ATF, hydraulic oil, and non-detergent synthetic motor oil — all of which are known to reduce friction between motor parts, improve the compressor’s longevity, and decrease the levels of overall energy consumption.
In the following article, we’ll be going through all the approved air compressor oil substitutes and comparing them. Then, we’ll end with a short QnA to clear up any remaining queries.
First, let’s start with the basics.
What is Air Compressor Oil?
Different machines require different sources of energy. Air compressors are fuel based and use a unique kind of oil called air compressor oil.
This oil is different from other fuels and oils as it’s formulated to prevent the inner parts of the machine from wearing out or causing damage through excessive friction. Unlike motor oils, air compressor oils contain no detergents and less carbon and sulfur.
Here are some notable features of air compressor oils –
Compressed air can generate heat which can disturb the inner working of an air compressor. So, air compressor oil helps by absorbing the heat and keeping the temperature of the compressor at a constant. This eventually aids in preventing heat damage and worn-out parts.
Air compressor oils carry certain additives which helps to preserve the life span of the compressor. This specialized formula helps to increase longevity by reducing friction, protecting the machine’s part in various conditions, and absorbing/redistributing heat.
Water and oil droplets, known as emulsions, can have severe and irreversible effects on an air compressor. That’s why air compressor oils are formulated to evenly separate water and oil to prevent emulsions.
Most motor oils will lose their viscosity when the temperature drops. They harden, clump together, and become useless. Air compressor oils on the other hand don’t have this problem, as they are able to retain their viscosity even when it gets cold.
Reduces Oxidation and Prevents Foaming
When the compressor is active, bubbles float to the surface of the oil and cause an accumulation of foam. This increases the exposure of oxygen to the oil, causing increased oxidation. Eventually, the oil separators become saturated with oil which results in a drop in pressure, higher energy consumption, and reduced longevity.
To prevent this from happening and causing damage to the compressor, the oil is formulated with additives that slow down oxidation and acid formation.
Different Substitutes for Air Compressor Oil
Given the many unique additives of air compressor oil, it’s understandable why this oil is so hard to find and sometimes very costly. If you’re unable to get access to regular AC oil, you can opt for a few substitutes.
Substitutes for air compressor oil work fine and are hassle-free most of the time. They are also relatively cheaper and easier to acquire, which cuts down costs and effort. These are the most common alternatives for AC oil.
Automatic Transmission Fluid (ATF)
ATF, better known as automatic transmission fluid, is a fluid used generally for automotives (especially car transmission) but is a suitable alternative to air compressor oil.
This fluid has a number of benefits that are similar to the features of air compressor oil. Just like AC oil, ATF also cools the inner parts of machinery and maintains a constant temperature, it prevents breaking down under pressure, and it reduces friction to combat wear and tear.
Automatic transmission fluid also has a couple other properties, this includes acting as a hydraulic fluid/medium and keeping the parts of machinery clean and free of debris.
Another great alternative to air compressor oil is hydraulic oil. Again, this substitute also has properties that are parallel to those of AC oil. One of these similarities is its viscosity.
As we’ve mentioned before, AC oil is unique for not losing its viscosity even when temperatures drop. Similarly, hydraulic oil carries a low viscosity property to flow flawlessly in cold weather.
Moreover, hydraulic oil does not oxidize, which means you don’t have to worry about foam or corrosion like you would with AC oil.
Motor Oil (Non-detergent, Synthetic)
Regular motor oil contains detergents which can cause carbon buildup, which can end in disaster. So, it’s best to go for non-detergent motor oil instead.
Non-detergent motor oil is inexpensive, is a great lubricant to reduce wear and tear, and helps to prevent overheating. For these reasons, it’s better than regular motor oil, however, to be on the safe side we recommend using synthetic motor oil.
Synthetic motor oil is workable in almost all temperatures, it forms little to no carbon buildup, and it has better longevity in comparison to mineral-based motor oils. While most air compressors say to strictly stick to AC oil, some of them allow you to use non-detergent 10w30 synthetic oil (but only during emergencies!).
Comparison: ATF, Hydraulic Oil, and Non-detergent/Synthetic Motor Oil
All the substitutes we’ve listed are completely safe to use and have been used as alternatives to air compressor oil for a long time. But, how do you decide which one to use?
ATF, non-detergent motor oil, synthetic motor oil, and hydraulic oil all carry properties which align with the features of air compressor oil. However, they also have their own properties which set them apart from each other and cause advantages as well as disadvantages.
So, here are all the pros and cons of our air compressor substitutes to help you compare between them –
Automatic Transmission Fluid (ATF)
- Helps to keep temperatures constant by preventing overheating
- Good lubricant, prevents friction between parts
- Combats wear and tear, carries corrosion fighting properties
- Widely accessible, found in many automotive stores
- Fights debris and dust from accumulating inside AC
- Contains detergents which cause grit and carbon buildup inside pump
- May cause leaks due to low viscosity
- Excellent lubrication, reduces friction between inner parts
- Prevents overheating of machinery, keeps temperatures constant
- Fights against rust formation
- Does not oxidize, no formation of foam
- Can be found in most hardware stores
- Not suitable for compressors over 20 gallon capacity
- Costly compared to other substitutes
Non-Detergent Motor Oil (Mineral and Synthetic)
- Cheap and readily available in every hardware store
- Evenly lubricates internal components of compressor
- Keeps temperature constant and prevents overheating
- Recommended by air compressor labels as best alternative
- Can cause some carbon buildup
How Often Does an Air Compressor’s Oil Need to Be Changed?
It is recommended to change the oil of your air compressor once it’s reached approximately 1,000 total hours of use. This means roughly 5-6 weeks of continuously using the same oil. So, it’s important to keep track of how long you use your air compressor for so you know when to change the oil.
On the other hand, your air compressor’s manual might have a different guideline for changing the oil. In that case, you should consult the manual before using the air compressor and change the oil according to the recommended time.
If you rarely use your air compressor or don’t keep track of the hours you do use it, it’s best to change the oil at least once a year to be safe. But if you use the AC 4-5 times a week or for long periods of time, it’s better to change the oil twice or thrice a year.
As for substitutes, it’s hard to say how long each alternative lasts and needs to be changed. To avoid mishaps, change it regularly. If you want to be on the safer side, use synthetic motor oil over mineral based motor oil as it lasts longer and you don’t need to overthink about changing it.
Frequently Asked Questions
1. Can I use SAE 30 oil in my air compressor?
Air compressors generally recommend using SAE 30 or SAE 20 oil, so it’s fine to use SAE 30 in your AC. SAE 30 is best for use in warmer temperatures while SAE 20 is better for cold environments. Plus, SAE 30 is thicker than SAE 20.
2. Can I use 10W30 in my air compressor?
10W30 is a multi-viscosity motor oil which can cause a lot of foam formation and lead to rust. It also contains detergents, which is known to cause irreversible damage to inner components of air compressors. Avoid this oil at all costs!
3. Can I use regular oil in my air compressor?
Regular motor oils (mineral based oils) tend to have poorer longevity compared to synthetic motor oils and can cause more carbon buildup. So, use synthetic motor oil instead.
4. Is compressor oil the same as hydraulic oil?
Hydraulic oils contain zinc which AC oils do not. AC oil contains oxidation inhibitors while hydraulic oils naturally do not oxidize. Moreover, air compressor oils separate better from water unlike hydraulic oils.
It is always a better option to use the intended fluid for a machine. That is why we recommend not using air compressor oil substitutes habitually, but rather using them whenever there’s an emergency.
Also, make sure to stick to the guidelines mentioned in the user manual of your air compressor, as it might say to completely avoid alternatives altogether. Even if you take the chance to use a substitute, make sure you do it safely.