How much oil should be added during maintenance and servicing of a screw-type air compressor?

Basic Principles for Oil Additions

The oil‑filling quantity for a screw‑type air compressor does not follow an absolute, fixed standard; rather, it is determined by the unit’s displacement, its design, and the capacity of the oil‑gas separator tank. During maintenance, the most critical principle is…Strictly follow the operation and maintenance manual provided by the equipment manufacturer.The manual clearly specifies the engine oil capacity and the recommended oil level markings for both the standard shutdown and operating conditions of this model.

How to accurately determine the amount of engine oil to add

In practice, determining whether the engine oil has been topped up adequately relies primarily on checking the oil dipstick (oil level indicator). The specific steps are as follows:

• Downtime Status Check: After the equipment has been completely shut down and the system pressure has been fully relieved, observe the oil level sight glass. At this point, the oil level should be at the position indicated on the sight glass.Upper limit scale lineNearby.
• Operational Status Check: Start the equipment and allow it to run; once the oil temperature has reached its normal operating level, check again. At this point, as the engine oil circulates through the system, the oil level will drop slightly; it should generally remain within the range indicated by the dipstick.From the centerline to the lower limit scale lineBetween.
• Add in stagesWhen adding engine oil, proceed slowly and monitor the level as you pour; never pour in a sudden, forceful stream, as this could overfill the system.

The hazards of overfilling or underfilling engine oil

The oil level must be maintained within an appropriate range; any deviation from the specified standard can adversely affect the equipment.

• The harms of adding too muchExcessive engine oil can increase the load on the oil‑gas separator, raising the risk of oil carryover and leading to elevated oil content in the exhaust. At the same time, excess oil increases the operating resistance of the main engine, resulting in higher running current, elevated exhaust temperatures, and accelerated oil degradation.
• The harms of adding too littleInsufficient engine oil directly leads to inadequate lubrication, resulting in accelerated wear of the main‑engine rotor and increased vibration. In severe cases, this can trigger an over‑temperature alarm and even cause the main engine to seize up, leading to major equipment failure.

Recommendations for Oil Management in Routine Maintenance and Upkeep

In addition to monitoring oil‑fill levels, routine oil management is equally important. It is recommended to check the oil level regularly and promptly top up with the same grade of oil if it falls below the lower limit mark. Furthermore, be sure to change the oil and oil filter according to the prescribed service intervals, and never mix compressor oils from different brands or grades. Before adding new oil, ensure that all old oil has been completely drained from the oil–air separator tank and thoroughly clean any contaminants from the oil‑circulation system to maintain a clean and unobstructed lubrication system.