3 Air Compressor Oil Substitutions: Here’s What You Can Use

Oil-lubricated air compressors have their benefits, but they also tend to require a fair amount of maintenance. Most importantly, the oil needs to be checked and changed regularly. So if you need to top off your oil or your compressor is in desperate need of an oil change, but you’re all out of your regular compressor oil, what can you do?

Fortunately, you’re not without options. There are a few air compressor oil substitutes that can work well in a pinch. They are:

  • Non-Detergent Motor Oil
  • Hydraulic Oil
  • Automatic Transmission Fluid

I’ll go over each of these in more detail below to give you a picture of their benefits and drawbacks. But it’s important to keep in mind that none of these should be considered long-term substitutes for your manufacturer’s recommended air compressor oil – they are best used only for short-term use and in emergencies.

1. Non-Detergent Motor Oil

Motor oil can be used in place of air compressor oil, but it needs to meet a few important criteria if you don’t want to damage your compressor pump.

Non-Detergent or Bust

Most importantly, any oil you put in your air compressor should always be labeled as “non-detergent” or ND. Detergents are added to many motor oils to help clean the internal components of combustion engines. In an air compressor, detergents can prevent grit from sinking to the bottom of the oil sump, and instead, keep it suspended in the oil. This will lead to buildup on the piston and cylinder walls that can damage the motor.

Oil Viscosity

Another important consideration when using motor oil in your compressor is viscosity. Most compressors use SAE 30 or SAE 20 oil. The former is ideal for warmer temperatures, while the latter is better for colder temperatures (SAE 20 is thinner, so makes startup easier in cold environments).

It’s always best to use the oil viscosity (often referred to as “weight”) closest to that of your original compressor oil. Your compressor’s user manual should specify what viscosity of compressor oil to use, and may even list acceptable motor oil substitutes. 

Along these lines, unless your manual specifically recommends it, it’s best to avoid using multi-viscosity oils (such as 10W30), as these can foam up when used in an air compressor. 

Mineral Vs. Synthetic

In general, it’s best to use synthetic oil because it tends to work best at different temperatures, creates less buildup inside the pump, and lasts longer than regular mineral-based oils. That being said, it won’t make much of a difference if you’re only using it in your compressor short-term (which is recommended).

All in all, general-purpose non-detergent motor oil will provide the necessary lubrication and cooling to keep the motor running and prevent overheating. But unless you happen to have non-detergent motor oil of the correct viscosity laying around, this likely won’t be any more convenient than running to your local hardware store for more compressor oil.

Non-Detergent Motor Oil Pros & Cons

Pros

  • Provides lubrication for internal pump components.
  • Helps prevent overheating.
  • Relatively inexpensive.
  • Available in most hardware/automotive stores.
  • Many manufacturers list it as an acceptable temporary alternative.

Cons

  • Limited by viscosity/type of oil.
  • Non-detergent oil is less common (less likely to have on hand).
  • May void manufacturer warranty if used.

2. Hydraulic Oil

Hydraulic oil is another viable substitute for air compressor oil in a pinch. Hydraulic oil essentially falls under the category of hydraulic fluid – the distinction has to do with its composition and what it’s used for. 

Hydraulic oil is primarily used as a medium for transferring power in hydraulic machinery (power steering systems, aircraft controls, hydraulic lifts, etc.) but it also serves many of the same functions as air compressor oil – lubrication, cooling, and corrosion/oxidation control, to name a few. As with motor oil, there are a few things to consider before pouring hydraulic oil into your air compressor.

Type

Most importantly, you don’t want to use just any type of hydraulic fluid you happen to have around – brake fluid and power steering fluid may technically be hydraulic fluids, but they’re formulated specifically for their respective systems and may damage your compressor pump. 

Instead, it’s best to use basic, universal hydraulic oil labeled along the lines of, “for use in all hydraulic systems.” This can typically be found at any hardware or auto parts store. And as with motor oil, you’ll want to avoid any oils that contain detergents. Most hydraulic oils do not contain detergents, but a few do so make sure to read the label carefully.

Some hydraulic oils are labeled as AW, which stands for “anti-wear” – this means they contain additives to protect against corrosion, oxidation, and other damaging forces. This is desirable, as long as it does not contain any detergents.

Viscosity

In some cases, hydraulic oil viscosity is measured on the ISO scale rather than the SAE scale, but they are fairly similar. Most hydraulic oils are either ISO 32 or ISO 46 – as with SAE ratings, the higher the number, the thicker the oil. 

Since most compressors take SAE 30 oil, your best bet is to stick with ISO 32, especially if your compressor is in a cold environment – but either grade should work fairly well in moderate temperatures. In general, a good rule of thumb is to stay close to the viscosity rating of your compressor’s normal oil.

Hydraulic Oil Pros & Cons

Pros

  • Provides lubrication and cooling for internal components.
  • Available in most hardware/automotive stores.
  • Most types protect against rust/corrosion.

Cons

  • Can be fairly expensive compared to other alternatives.
  • Less common than other alternatives.
  • Isn’t suitable for larger compressors (20-gallon+).
  • May void manufacturer warranty if used.

3. Automatic Transmission Fluid (ATF)

Surprising as it may be, another popular alternative for air compressor oil is automatic transmission fluid. Being a type of hydraulic fluid, it shares many of the same properties as compressor oil and the other substitutes listed above. And many homeowners tend to have a spare quart of transmission fluid hanging out in their garage, which makes it a fairly convenient backup option in an emergency. That being said, it also has some major downsides worth paying attention to.

Additives

ATFs typically contain additives to help prevent corrosion and oxidation, which can help extend the life of the compressor. However, most ATFs contain detergents that can cause carbon and grit buildup inside the pump, leading to premature wear. This makes ATF the least desirable choice of all the alternatives, especially for long-term use.

Viscosity

ATF viscosity is also generally much lower than that of typical compressor oil. While this may offer an advantage in very cold temperatures in terms of startup capability, it may not provide adequate lubrication during operation and can even lead to internal leakage as the thinner fluid gets past the seals on the piston.

Automatic transmission fluid may work in an emergency, but due to the above reasons, it should probably be the last resort.

ATF Pros & Cons

Pros

  • Helps prevent overheating.
  • Protects against corrosion.
  • Usually more convenient than other alternatives (found in most homes and sold in any auto parts store).

Cons

  • Contains detergents that can damage the compressor.
  • Low viscosity can lead to inadequate lubrication and internal leaks.
  • May void manufacturer warranty if used.

Other Considerations When Using Compressor Oil Substitutes

Now that you know the three compressor oil alternatives, there are a couple of things to keep in mind before you use them.

Warranty

As you probably noticed, a common disadvantage among all of the above alternatives is the warranty. Most air compressor warranties stipulate that the warranty will be voided if you use anything other than the manufacturer’s recommended lubricant in the compressor – whether that’s a specific brand or simply a particular grade of compressor oil. 

As mentioned above, some user manuals will list suggested alternatives to compressor oil, but make sure you read your manual carefully to ensure that even these won’t affect your warranty. If your compressor is still under warranty, it may be worth the inconvenience and work stoppage to go out and find the correct oil that meets your warranty’s requirements.

Mixing Lubricants

It’s also very important never to mix different types or grades of oil. So if you simply need to add more oil to your compressor, make sure you only use exactly what’s already in there. If you need to switch to a substitute, always drain the current oil completely and flush the system (if possible) before you add the new fluid.

As you can see, it’s best to stick with air compressor oil when possible, but with these guidelines, you can safely use alternatives if you need to. But it never hurts to have extra compressor oil on hand! With that in mind, let’s go over some basics of general maintenance for your oil-lubricated compressor.

Why It’s Important To Change Your Air Compressor Oil Regularly

Just like the oil in your vehicle’s engine needs to be changed periodically, so does your air compressor oil.

As your compressor’s pump runs, the oil is splashed onto the piston and crankshaft (or similar mechanical components in other types of compressors). Over time, small amounts of dirt, carbon, and other grit accumulate in the oil from normal use. The oil itself will also break down from heat and friction, and any additives (anti-rust agents, demulsifiers, etc.) in the oil will become less effective. 

The result will be thicker, sludgier oil that no longer provides adequate lubrication and can deposit grit (which would otherwise sink to the bottom of the oil sump) on the mechanical parts. This can lead to overheating and excessive friction that will strain the pump motor and rapidly wear out or damage the pump.

How Often Should You Change Your Air Compressor Oil?

Generally speaking, you should change your air compressor oil every 1,000 hours of use, at least. However, your compressor’s user manual should state the recommended oil change schedule of your specific model. Whether you use mineral or synthetic oil also affects how often you need to change it.

It may not always be practical to log how many hours you use your compressor for every time you use it, but it doesn’t hurt to keep track of a ballpark figure. 

Alternatively, a good rule of thumb is to change your oil once a year if you only use your compressor occasionally. If you use your compressor several times a week for more than a few minutes at a time, it’s a good idea to change your oil even every six months or so.

In addition, synthetic oil tends to last much longer than regular mineral-based oil, so you may be able to stretch your service interval even further. When in doubt, consult your owner’s manual for specifics on the oil type and service schedule for your particular model.

Thanks for reading!

Justin

Justin is a full-time blogger with a passion for anything DIY. When he's not hanging out with his wife and son, you can find him putting the finishing touches on yet another home project he's taken on. He's also the creator of AllAboutAirCompressors.com.