Like many of the questions this site receives about air compressors, “what oil do I use in my compressor ” is one that has multiple answers. If you are looking for an answer as to what oil you use in the air compressor, please read on.
Depending on the make of air compressor, you may need to add one or more of the following oils to your air compressor:
→ no oil at all
→ compressor pump lubricating oil
→ rotary screw or vane compressor air-end oil
→ compressor gasoline or diesel engine oil
What Oil Do I Use In My Compressor – No Oil At All?
So many of the small, DIY type air compressors found for very little money at the big box stores – like the Porter Cable compressor shown – no longer require additional lubrication. They are permanently lubed at the factory, meaning that the compressor owner no longer has to ensure that there is oil and that the oil level in the sump is maintained.
Which is not to say that industrial quality air compressors, large air compressors, cannot be lubrication free. There are many applications in manufacturing that require no oil in the compressed air stream, and one way to achieve that is to have an lubrication free air compressor.
Before you worry about what oil to use in the compressor then, first make sure that your make and model of air compressor is actually oil-lubricated. If it is, then the information you need follows.
Compressor Pump Lubricating Oil
Quite a number of smaller air compressors require the addition of pump lubricating oil, as do many industrial compressors, like the compressor pump shown next.
The white circle shows the oil fill port and the red circle outlines the sump drain.
Smaller oil lubricated compressors often have an oil fill tube, with either a sight glass to show the sump oil level, or the oil fill tube cover will have a dip-stick to help determine safe oil level for that compressor, perhaps similar to the one shown.
If your air compressor has an oil sump, and a method of adding and checking the oil level, you will need to add pump lubricating oil when the new compressor is brought home and before use, and add oil as the compressor consumes it while it is running.
What Compressor Oil?
If the air compressor is under warranty, either review the compressor manual or contact the company from which you purchased it, and determine what compressor oil they recommend. That’s because, if the pump is under warranty, and you use a non-specified oil, then you might void the warranty for that compressor.
If the compressor is no longer under warranty, if you visit the hardware store and purchase Compressor Pump Lubricating Oil, that oil will typically suffice for lubricating the compressor pump.
Non-Detergent Oil Only
If you purchase other than compressor lubricating oil, even if the other oil has the same thickness and heat resistance, it may not work properly in the compressor pump.
Automotive oil, for example, is lubricating oil. It also has chemicals and detergents in it that will lift abrasive materials into the oil and keep them in suspension so they can be stripped from the oil by the oil filter.
The compressor pump typically does not have an oil filter, and it is preferred if any debris in the oil sinks to the bottom of the sump, to be drained out during the next oil change.
If you are an on-line shopper, simply Google compressor lubricating oil and you will find many sources. Just make sure what you purchase is labeled as Compressor Lubricating Oil or Compressor Pump Lubricating Oil, and you will be fine.
Rotary Screw or Vane Compressor Air-end Oil
Oil helps seal the air compressor process in vane type compressors, yet it is the rotary screw compressor pump that runs entirely bathed in oil.
Regardless of whether the compressor is under warranty or not, I would use the air-end oil that is specified for my compressor by the manufacturer. Why second guess the expertise of the compressor manufacturer? You selected that type of compressor as it best suited your compressed air needs, so “stick with the one that brung ya” is my advice.
For more information and photos of air end damage due to insufficient lubrication, visit: http://www.airends.com/lubrication_problems.htm.
And that brings us to the oil used to lubricate the engine on a:
Diesel or Gasoline driven air compressor
The type of oil used in towed, gasoline or diesel driven air compressors, is similar to that used in automotive oil systems. This type of oil will have a variety if viscosities and will contain additives including detergents to help remove particulates from the lubrication system.
When a vehicle requires lubrication, typically one would check with the manual to see what oil was specified. The same holds true for the diesel or gasoline motors used to drive an air compressor.
Either use the manual to determine the correct oil, or contact the company that manufactured the engine for their recommendations.