Air compressors have many parts that move fast and, like any mechanical machine, require lubrication to work smoothly, reduce friction, and prevent premature wear and tear.
Unless your compressor is an oil-free model, you should periodically replace the air compressor oil. This article will discuss the best way to lubricate your compressor and what to do if you don’t have special oil handy.
Air compressor oil is a specially formulated lubricant with medium viscosity to reduce friction. The lubricant may be either,
- Mineral oil-based or
- Synthetic oil (non-detergent).
More on the air compressor oil types are explained later in this article.
Air Compressor Oil Alternatives
If, for some reason, you can’t use compressor oil and you are wondering if there is another oil you can use, below you will find some alternatives that can be suitable. It’s always better to use one of these substitutes than to use your compressor with low or no oil at all. But I suggest you use them for an emergency and go back to the right oil as soon as possible for your compressor’s sake.
1. Automatic Transmission Fluid (ATF)
There are many types of ATF. Not all of them are suitable for compressors, but some can be used. Synthetic ATF is safer to use than standard ATF and will help you keep your compressor lubricated.
Using transmission fuel as a substitute oil has the following benefits.
ATF Pros:
- No breakdown from the heat produced by air compressors.
- It doesn’t produce many deposits and sludge.
- Automatic transmissions use it to power valves and operate under pressure, so it’s designed to endure compression. ATF is designed to withstand compression without degrading.
ATF Cons:
- It doesn’t blend well with the compressor’s oil. You will have to flush your compressor before using ATF on it.
- Some of the detergents ATFs use are harmful to air compressors.
- It doesn’t handle water contamination well, reducing its lifespan.
- They will void your compressor’s manufacturing warranty.
2. Hydraulic Oil
It can be a good alternative for air compressor oil. Its low viscosity makes it even better when used in cold temperatures. Hydraulic oil doesn’t oxidize and is a good alternative as long as you don’t use your compressor for extended periods.
Pros:
- It can be a good substitute when used for a short time and even better when used in cold weather.
Cons:
- It doesn’t stand high temperatures well, so it can fail to lubricate your compressor in hot weather or when you need to use it for extended time periods.
- Hydraulic oil contains zinc, while compressor oils don’t. Zinc can be harmful to your compressor.
- Hydraulic oil doesn’t have good water separability, an essential quality of good compressor oil.
3. Motor Oil (Non-Detergent Synthetic)
Synthetic motor oil should be considered as the last option. If you have no choice between using your compressor without oil (which would be catastrophic) and using motor oil, then this is the lesser of two evils.
Never use any motor oil with detergent in your compressor because it’s extremely harmful to it. If you manage to find non-detergent synthetic oil, a task that sometimes can be harder than finding oil specifically made for compressors, then you can use it with care. Besides, non-detergent motor oil can be more expensive than compressor motor oil, so it only makes sense to use it if you happen to have it at hand.
Pros:
- It’s a good substitute to be used for a short time.
Cons:
- It’s expensive and hard to get.
Type of Oil for Air Compressors
The type and grade of oil vary depending on the compressor’s manufacturer. The idea is to find a lubricant that benefits your compressor and reduces friction between the moving parts to extend the compressor’s life span as long as possible and, at the same time, use a product that suits your needs in terms of budget. An industrial compressor that runs all day long in a factory is not the same as a compressor used occasionally for a hobby.
Today, oil companies spend lots of resources and time developing high-quality oil for different machines, including air compressors. Like in the car industry, you will find two main types of oil: natural and synthetic.
The difference between compressor oil and motor oil is that it is detergent-free and has less carbon and sulfur.
Using the right type of lubricant will also keep your air compressor quiet. All this being said, let’s take a look at the different types of compressor oil available in the market.
Standard Oil
This oil is made from a mineral oil base. It’s cheaper than synthetic oil and is recommended for economic compressors or hobbyists.
If you don’t use your compressor professionally or you don’t use it for long periods, you should still make some considerations. Many people fall under the wrong assumption that home compressors are cheap and less important than industrial compressors, but you and only you know what your compressor means to you and how much you want to spend to take good care of it.
Synthetic Oil
This oil is more advanced and thus more expensive. Oil manufacturers spend much time and resources researching and developing it, resulting in a technologically advanced oil that includes many additives and provides much more protection than standard oil. As synthetic oil is used in other applications, synthetic compressor oil is multi-grade, which covers a wider temperature range than standard oil. Besides, it’s less contaminating than standard oil and less prone to leaving residues and unwanted particles stuck to the compressors’ moving parts.
Although expensive, synthetic oil has many advantages over standard oil, whether you are using a reciprocating or a rotary screw compressor type.
Some of the main benefits of synthetic compressor oil are:
- Long Life: Synthetic compressor oil can last up to 8,000 hours when used in a rotary screw compressor and 2,000 hours in reciprocating compressors. It means it lasts about three times more than standard oil.
- High Heat Absorption Capacity: Compressing air produces a lot of heat. Synthetic compressor oil helps to keep the compressor cooler, relieving stress on its moving parts.
- Oxidation Resistance: This helps to extend the oil change intervals and to protect compressors’ inner parts better for long intervals.
- Improves Water Separation: Synthetic oil for compressors is designed to separate water, protecting the compressors’ moving parts from moisture and keeping rust away. This is important because compressing air generates water, and no one wants water inside it or in the compressed air.
- All Weather Friendly: Standard oil tends to lose efficiency in cold and hot weather. Synthetic compressor oil keeps its viscosity and resists high temperatures extremely well in cold weather.
- Doesn’t Produce Foam: Standard oil tends to produce foam when exposed to oxygen, which can lead to a saturation of the oil separators. This doesn’t happen with synthetic oil, which extends the compressor’s lifespan and increases its efficiency.
- Fewer Deposits and Carbon Buildup: Synthetic oils produce small to zero deposits, varnish, and sludge. This is great for extending compressors’ life and reducing maintenance costs.
What Weight Is Air Compressor Oil?
If you can’t find this information in your compressor’s user manual, this information can be of help. If you plan to use standard oil, it’s fine to use 20 or 30-weight compressor oil.
The weight indicates the oil viscosity; a higher weight means more viscosity and better protection in warm climates. However, if you use your compressor in cold weather, you should use lighter oil, and 20 would be just fine. If you are using synthetic oil, you can use a multi-grade 20-30 oil.
Oil Changing Frequency
It’s always best to check your compressor’s user manual and follow the manufacturer’s guidelines.
If you can’t find this information, it may help to know that standard air compressors (reciprocating) need to have their oil changed between 1,000 to 2,000 service hours or three months.
The rotary screw compressors can run longer without an oil change, usually between 7,000 to 8,000 operating hours or once a year.
Should You Buy Special Compressor Lubricant?
Manufacturers will generally advise you to use specific oil, but using oil better than required won’t do any harm. In the worst case, you won’t notice any advantage over standard-spec lower-quality oil, but you won’t damage your compressor. On the other hand, using oil of a lower quality than the one specified by the manufacturer can harm your compressor or reduce its lifespan.
When buying oil, you should ask yourself some questions such as:
- What kind of compressor am I using?
- Is it expensive?
- How frequently do I use it?
- How complex is my compressor?
- How hard is it to change its oil?
- Is it worth buying oil that will allow longer oil change intervals?
Consider all the pros and cons and the consequences of using cheap versus high-quality and expensive oil.
FAQ
Can I use 10w30 oil in my air compressor?
You should avoid using 10w30 oil in your air compressor because this type of oil has many detergents that are harmful to your compressor. Always ensure using detergent-free oil in your compressor, starting from a weight of 20 to 30.
Do all types of air compressors need oil?
Some compressors don’t need oil; they are called oil-free compressors. These utilize special coating on moving parts and are designed to be maintenance-free.
Can I use the bar and chain oil in my air compressor?
Even though some bar and chain oils weigh 30 and are detergent free, they are sticky and shouldn’t be used in your air compressor.
Can you put vegetable oil in an air compressor?
You shouldn’t put vegetable oil in an air compressor, mostly because it’s too thin. Besides, it’s prone to leave deposits that create sludge and can even stick to the compressor’s moving parts.
How to tell if an oil is non-detergent?
Read the label. If it’s non-detergent oil, it should read API SA.
If the label reads API CL, it contains detergent; if it doesn’t specify, assume it has detergent.
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