Compressor Oil Change Operation Guide

The service life of lubricating oil mainly depends on the operating environment of the compressor. Moisture and dust in ambient air are key influencing factors. 

The filtration accuracy of oil filters is generally no less than 15 microns, which means dust particles smaller than 15 microns will circulate together with the lubricating oil. 

Oil replacement is mandatory when the concentration of dust particles below 15 microns becomes excessive.

Moisture contained in compressed air causes emulsification of lubricating oil, resulting in loss of lubrication performance. Moisture triggers metal corrosion, 

and large quantities of corrosion particles smaller than 15 microns also circulate within the lubricating oil. Oil change is an important measure to extend compressor service life. 

Using lubricating oil with shorter replacement cycles is more beneficial to machine reliability.

During operation, compressor lubricating oil is subjected to heating, oxidation, high-speed shearing, dust contamination and harmful gas exposure. 

Oxygen reacts with hydrocarbons in the lubricant, gradually oxidizing the oil, darkening its color and raising viscosity. In severe cases, 

oxidation products can no longer dissolve in the oil and precipitate as brown viscous sludge inside the system. Such sludge easily blocks control oil passages in components, 

accelerating wear of ball bearings, valve spools and other parts, and disrupting normal system operation.

Oxidation also leads to corrosion and acidification. The oxidation process starts slowly. As sediments and acid values accumulate and viscosity rises to a certain threshold, 

oil replacement is required. If neglected, oxidation accelerates continuously along with viscosity increase, which further elevates operating oil temperature. As oxidation intensifies, 

compressor oil viscosity rises noticeably. Once the oxidation rate shifts from linear growth to exponential growth, viscosity rises even faster and undesirable equipment failures may occur.

If waste oil cannot be thoroughly drained during compressor oil change, newly filled compressor oil will be contaminated. Residual waste oil introduces massive free radicals and accelerates oxidation, 

cutting the service life of new lubricating oil by half.

1. Thoroughly clean the oil-gas separator, oil pipelines and oil cooler. Drain all waste oil completely before oil change. When replacing the oil-gas separator element, carefully clean the separator housing. 

2. Determine whether purging of the oil cooler is required according to on-site conditions; perform cleaning before adding new oil.

3. Add 3%~5% cleaning agent into the old compressor oil. Run the unit under normal operating conditions for 6~24 hours, then drain all oil from the system. Replace the oil filter and fine oil-gas separator elements, 

   If sludge or carbon deposits generated by long-term use of mineral oil or low-grade oil have not been fully cleaned, extend the cleaning duration appropriately, generally 2~3 days, which will not harm the system. 

4. If suspended sludge, carbon deposits or gum formed during cleaning block the filters and trigger unit shutdown, replace the filters and continue cleaning.

5. fill with new compressor oil and start the unit for normal operation.

6. Drain all waste oil from the compressor, fill with No.5 spindle oil, run the unit under low pressure for 5~10 minutes, then drain all spindle oil completely before adding new compressor oil.

   Store the drained spindle oil properly (5-gallon food-grade plastic pails are recommended; sediments can be separated before reuse) for the next oil change. 

7. There is no need to worry about the low flash point of spindle oil. Low-viscosity spindle oil features high flow rate, low discharge temperature and strong flushing capacity to achieve effective cleaning.

8. Drain all waste oil from the compressor and fill with No.5 spindle oil. Run the unit under low pressure for 5~10 minutes and drain fully. Purge oil pipelines (including the oil cooler) and oil-gas separator with compressed air or bottled nitrogen. 

9. After thorough purging, add new compressor oil.

10. Qualified users may engage professional lubricant service providers with advanced expertise to clean the compressor oil circuit and conduct oil replacement.
11. After filling new oil, add SL anti-wear repair agent at a ratio of 0.5% of the weight of new oil. This not only extends bearing service life, but also doubles the service life of compressor oil, as the SL anti-wear repair agent contains antioxidants.