Why do rotary screw air compressors need oil?
Air compressor oil plays several vital roles within a rotary screw air compressor system:
- Lubricates moving parts
- Creates a seal between rotors to trap air
- Prevents premature wear on parts
- Helps cool air during compression
Rotary screw air compressors are sometimes “oil flooded” or “oil injected,” describing that oil is injected into the rotor housing. The oil mixes with the air during compression but is separated back out before the compressed air leaves the system.
Some rotary screw air compressors don’t require oil at all. However, these designs tend to be louder and more expensive. Oil-free rotary screw air compressors are typically only used in industrial applications in which oil contamination absolutely can’t occur, such as food processing or medical oxygen.
When should I change air compressor oil?
Maintaining proper service intervals will keep your air compressor running in optimal condition and help maintain the warranty. You should always check and follow your air compressor manufacturer’s service maintenance schedule.
For example, here is a breakdown of VMAC’s air compressor oil service intervals:
System |
Compressor Type |
Oil Service Intervals |
G30 |
Gas Powered |
200 Hours / 6 Months |
D60 |
Diesel Powered |
500 Hours / 6 Months |
H60 |
Hydraulic Driven |
500 Hours / 1 Year |
DTM70 |
PTO Driven |
200 Hours / 6 Months |
UNDERHOOD™ 70 |
Engine Mounted |
200 Hours / 6 Months |
As you can see, the service hours and periods range significantly between different air compressors—even when designed by the same manufacturer. Therefore, you should always check your air compressor’s manual when determining when to change the compressor oil for your system. Contact the manufacturer directly if you can’t locate a manual for your system.
Do I have to use VMAC oil?
VMAC cannot recommend alternate compressor oils. VMAC compressor oil is a synthetic lubricant specially formulated with an additive package for our rotary screw compressor that allows it work at the high rotor speeds, high air pressures, and higher temperatures our compressors run at. This lubricant also works properly in our Air/Oil Separation process.
Poor performance of, or failure of a VMAC system resulting from the use of non-VMAC compressor oil is not covered by VMAC Warranty.