Diester Compressor Oil

The Chemlube gets good reviews. I read somewhere that some compressor manufacturers private label it. I was surprised that my compressor initially did not come with a more specific oil requirement given the extreme operating conditions inside an HPA compressor. I wonder if there is a significant correlation between oil type/quality and mechanical breakdowns. Have you had any issues with either the Tuxing or Yong Heng compressor ?

I have noticed that a lot of people use the Royal Purple Synthetic reciprocatiing compressor oil with good results. The specifications look similar to the full synthetic oil I have been using and the Amsoil PC Series ISO100 SAE 30/40 oil that I was also looking at. However, I don't believe that any of those carry manufacturers recommendations explicitly stating they are recommended for High Pressure compressor use. On the other hand, most of the diester oils I have looked at, explicitly state they are recommended for HPA use. They also have the side benefit of being safer to breathe when using in a confined space.

It seems logical that significant differences in tolerances, temperatures, stresses, etc., between high and low pressure compressors would warrant a different type of oil for each. Yet it is mostly the higher-end HPA compressor manufacturers (Baur, Coltri, etc.) that specify diester-based oils. Maybe it is because those compressors are typically used for breathable air. Or maybe they are engineered significantly different. Maybe it really does not matter and breathing air aside, any good full synthetic will do. Unless I can find a good reason not to use a diester-based oil in my AV4500, I think I am going to give one of them a try at the next oil change.

Humdinger - I checked the comparison charts. Secolube 500 and Chemlube 501 are almost identical except for the vicosity. Secolube 500 is ISO 150 SAE40 vs. ISO100 SAE30 for the 501. AV recommends ISO 100, so I would probably go with the 501. What compressor are you using the Secolube in?

Good to hear. I am going to give the diester oil a try.

Edit: After further research and discusssion with an industrial compressor expert, I decided NOT to run Diester oil in my compressor. Diester oils have strong detergency action and less hydrolic stability than PAO based synthetic oils. Detergency is an issue because it will increase the suspension of contaminates and without sufficient oil volume and/or filtration methods, seals and other parts can be negatively impacted. Hydrolic instability can cause oil to break down in water and form carboxylic acid and other acids that can also damage machinery and rubber seals.

Many of the higher-end compressors recommend the use of diester based oils, however, they have been engineered with their specific use in mind. In the end, when it comes to the type of oil used, I think it is best to follow your compressor manufacturers recommendations.

The point is that not all oil properties are compatible with all compressor designs. I would expect and trust Bauer, Coltri, Nardi, etc., to specify the correct oil to use in their compressors. But that does not necessarily mean that that oil will work properly in all other compressors. Ester-based oils have properties that can harden rubber seals and cause other issues if the compressor was not specifically engineered to tolerate the use of that oil.

The question is not so much whether a good dedicated compressor oil should be used - I agree there is no evidence to support otherwise. The question is whether PAO and Ester based compressor oils are interchangeable. After looking into this I believe the answer to that is, it depends on the compressor and how it was designed.