The best synthetic air compressor oils can make a massive difference in the longevity of your compressor, as well as it’s the ability to start in cold weather.
While it’s nice to have an air compressor around, it’s not a totally maintenance-free tool to leave sitting in your garage (why you need to drain your air compressor). Many air compressors need oil to run properly.
If you’ve never changed the oil on your compressor, or you never knew you needed to, your first question will be what kind of air compressor oil should you buy? Tool Tally makes it easy. (Do you have an oilless compressor?)
What Kind of Oil for an Air Compressor?
Air compressors normally use synthetic or standard, non-detergent oils. If the manufacturer does not specify otherwise, you can use any standard 20-weight or 30-weight oil without detergents. Most commonly, this will be an ISO 100 oil (ISO 100 is a standardized industry measurement).
Following the manufacturer’s guidelines is always the most important.
There are, however, specific air compressor oils. They don’t cost much more than other types, and they are formulated for industrial use-cases, making them ideal for the day-to-day use of the local machine shop or job site.
If you want to make the best choice, you need to understand why your air compressor oil type matters.
(This post is about 2,300 words long. Read time ~ 8 minutes )
Do All Compressors Need Oil?
Some air compressors use lubricants. These compressors tend to have higher duty cycles and longer lifespan, such as these shop compressors.
Air compressor oil acts as a lubricant to keep the machinery inside running at full efficiency.
Oilless air compressors tend to have shorter lifespans and have a maximum CFM around 2-5 CFM than oiled compressors because the components experience more wear and tear. The cylinders and bearings come sealed from the factory with some amount of lubricant already inside and a non-stick type material coating the parts. It lasts well at first, but deteriorates quickly and cannot be re-lubricated.
Most shops use air compressors that need lubrication. They last longer and the maintenance is not difficult enough to be intimidating. All you need to do is get the right air compressor oil and change it every once in awhile (see maintenance intervals below), as well as topping it up as needed.
Types of Oil that Work with Compressors
Oil is oil, right? Not so fast.
B It’s easy to see the difference between things like cooking oil and car oil, but even individual car oils have variants. Similarly, air compressor oils are a different configuration from other common lubricants and are more similar to hydraulic fluid.
Motor oils, for example, often contain detergents that can harm an air compressor.
You should not use your leftovers from your last oil change to top up your compressor without making sure it is detergent-free.
3 Best Air Compressor Oils For Protecting Your Compressor
Air compressor oil is specialized. While you can find it fairly easily, you may not have a good selection everywhere you look. Most hardware stores and some auto parts stores will have air compressor oil.
But, if you don’t need the air compressor oil immediately, it’s easier to order it online. There’s an enormous selection so you’ll be able to find exactly what you need.
1. Powermate Px P018-0084SP Synthetic Air Compressor Oil
The Powermate is equivalent to a 20 weight air compressor oil that’s free from detergents and other additives. It’s a synthetic oil that’s designed to work in low-temperature ranges from 0 degrees F. If your compressor is having a hard time trying to start in the cold Minnesota mornings, this is the best choice for you! It is still suitable for warmer climates and serves as an all-around good air compressor oil. (If you have a much older unit (8+ years) and it is struggling to build pressure, stick with the 30-weight version below. This 20W will slip past the piston rings and push more lubricant into your hoses. )
2. Royal Purple 01513 Synthetic Air Compressor Oil
This a high-performance synthetic air compressor oil with the standard viscosity recommended by air compressor manufacturers. It’s measured to be an ISO 100 weight lubricant, which is hydraulic grade that is designed for highly-pressurized, closed, systems. Its viscosity is equivalent to SAE30 but without the harmful detergents of motor oil. This air compressor oil is designed to have a long shelf life, but it won’t be as useful in colder climates. For pumps that slave all day in the heat, this would be my first choice.
3. Campbell Hausfeld MP12 Standard Compressor Lubricant
The Campbell Hausfeld is a 30-weight oil free from detergents and other harmful additives. It’s a standard oil, not synthetic. This version is for normal temperature ranges and may not work as well in extremely cold temperatures. Made by one of the most well-known pneumatic brands, it is hard to go wrong with this formula for temperature-controlled shops. I especially prefer this one for older units where the Synthetic might get more blow-by and be used up more rapidly.
Characteristics of Compressor Oils
Air compressor manufacturers each have their own guidelines about what should and shouldn’t be used with their machines. Ultimately, these are the guidelines you want to follow. They should give the basic requirements for the type of compressor lubricant to use and may include guidelines for higher performance.
Look for these basic characteristics within their recommendations to know exactly what you need:
Oil comes in different thicknesses, which is known as the viscosity or “weight”. A higher viscosity means the oil is thicker while a lower viscosity means it’s more watery.
Most air compressors use a viscosity of 20 or 30. Viscosity is often called weight, so the oil might be labeled as 20 weight. Some lubricants are measured in the ISO scale, which can be matched to find the equivalent SAE weight.
Viscosity is the most important measure for a compressor oil. If it’s too thick or too thin, it may not work well in the machine and could cause it to shut down.
The other important measurement for compressor oils is the temperature range. Some oils might have the right viscosity, but they won’t operate as expected in every temperature range. Cold below freezing or heat about 120F can both cause it to behave differently.
You generally want a lower viscosity for cold weather and a higher viscosity to protect those metal parts during the heat of summer.
Keep in mind that heat is generated from the air compressor itself. Ideally, a 20 weight is great for colder weather while a 30 weight is best for temperate climates and all other situations.
Pay attention to the type of additives and detergents. Some oils have extra additives that are beneficial in car engines but will be detrimental to your air compressor. An example of this is detergent additives that are present in diesel engine lubricants. They help to clean diesel engines, but the same additives could ruin your air compressor motor over time by carrying metal particles in the lubricant as it moves about.
Additives that do help air compressors include elements that will help the motor resist corrosion or prevent rusting.
Synthetic Vs. Standard Air Compressor Oils
Lubricants can be made in two ways. They can be created using a mineral base or a synthetic base. Standard air compressor oils are mineral-based lubricants.
Synthetic compressor oils are more highly refined since they are made using a synthetically created base rather than an mineral base. They are a more refined oil that has gone through much more processing to engineer them for this specific use case.
Both can be used in most air compressors. Generally synthetic is the preferred option.
In many cases, synthetic air compressors oils are required for compressors. Screw compressors can get 8,000 hours of use between changes when using synthetics. This is mainly because they don’t contain some of the compounds found in standard oil that create build-up around the valve backs and faces. They also cause less carbon build-up. Many synthetics are better for compressor performance and longevity.
How Often Should You Change Compressor Oil?
There are two types of air compressors that need lubrication: reciprocating and rotary compressors. The more you use either of them, the more frequently it should be changed. For a reciprocating compressors, oil changes should be about every 3 months (800 hours). For a rotary compressor, they should be about every 7,000 hours of use.
For both types of compressors, you should change the oil a minimum of once per year, even if you don’t use it that much. Letting it sit for too long may cause it to break down over time and damage your compressor.
Each device may have specific instructions about oil changing requirements. See if your compressor’s manufacturer has any recommended change intervals.
How Much Oil Does an Air Compressor Need?
The size of your compressor will determine how much oil it uses. Most should not use more than a few ounces of lubricant at a time. The process for changing air compressor oil is as simple as unplugging, draining, and refilling again.
Air Compressor Oil Frequently Asked Questions (FAQ)
Compressor Oil Vs Motor Oil
Motor oils can get the job done if it doesn’t have detergents (which is hard to find). Detergents are designed to pick up the harmful matter and carry it to the oil filter of an engine. Most compressors don’t have a filter, so you don’t want the oil carrying harmful particles around inside the compressor. Instead, you want a nondetergent air compressor system that lets the particles fall to the bottom of the oil pain where they stay until the next time you change it.
Do Oil Brands Matter?
No. You don’t need to buy an exact brand that matches the brand of your compressor. It may be easier to match the brand to your compressor for simplicity’s sake, but it’s not a requirement. (In fact, most brands don’t offer any lubricants) Make sure that you get one that meets the manufacturer’s recommendations for your compressor, regardless of the brand.
When should I add more oil to my compressor?
You should only top up your air compressor’s oil level if it gets too low on the dipstick. You might hear the machine motor making more noise or feel it heating up more than usual. Check the dipstick weekly when using your compressor heavily. In most cases, it’s better just to change the oil rather than only topping it up, unless it is still clean or was recently changed.
What should I do if I overfilled the oil?
Most compressors have a drain plug that allows you to empty out the oil from the holding tank. If you think you overfilled the tank, you should locate the drain plug and drain the new oil and refill it again. In this case, it’s better to waste a little bit, than it is to risk damaging the compressor.
What happens when oil gets in the air lines?
Most air compressors have oil separators as a standard part of their motors. However, if there’s an issue with the separator or compressor pump, oil can be pushed into the air-lines. Small amounts of oil can find their way past the piston rings into the lines even in a good situation, but if there’s too much oil it could indicate overfilling, or failed piston rings.
Why is my compressor blowing oil from the outtake?
The most common reason for this is when the return line is not large enough or is clogged. This prevents the oil from returning to the tank as it should and sends it to the crankcase instead, where it can be drawn up and expelled through the outtake.
Is my compressor using too much oil?
If your compressor is using too much oil, there could be one of two problems going on: there may be a leak, either inside the compressor itself or outside it. Or, you may be using the wrong type and it’s not working properly within the compression chamber. This is more likely to happen if the oil viscosity is too low.
How do I stop premature oil failure?
To avoid this kind of issue, you need to avoid using your air compressors for long periods of time without stopping.
Premature air compressor oil failure happens because the compressor heats up and operates at very high temperatures for an extended period of time (exceeds duty cycle).
This results in a dangerous situation where oil is coating the inside of the compressor and degrading from the heat, which removes the protective properties and causes it to build. Change the oil before resuming work.
Getting the best air compressor for your type of use, is the best way to avoid oil failure.
As long as your air compressor oil is detergent-free, you can use any 30 weight viscosity. However, investing in a compressor-specific oil does not cost much more and may extend the life of the compressor.