How long is the typical service life of PAG synthetic oil?

The service life of PAG synthetic oil in compressors is generally 8,000–12,000 hours under normal operating conditions, equivalent to 3–5 years of service.

Under severe working conditions such as high temperature and heavy gas dilution, the service life is reduced to about 4,000–6,000 hours.

1. Typical service life by equipment

Screw compressors for natural gas, LPG and chemical gas

Normal condition: 8,000–12,000 hours / 3–5 years

High exhaust temperature & heavy hydrocarbon dilution: 4,000–6,000 hours

Refrigeration compressors & HVAC / vehicle A/C compressors

Automotive air conditioning: 2–3 years / 40,000–60,000 km

Industrial screw & centrifugal refrigeration compressors: 6,000–10,000 hours / 3–4 years

Reciprocating compressors for high-pressure gas, ammonia and acid gas

Standard condition: 6,000–10,000 hours

Service with H₂S and corrosive gas: 3,000–5,000 hours

Vane compressors & CO₂ process gas centrifugal compressors

Stable-load centrifugal units: 8,000–15,000 hours

Vane compressors: 6,000–10,000 hours

2. Key factors affecting service life

Temperature (the most critical factor)

If oil temperature exceeds 90°C, the service life will be reduced by about 50%. The oxidation rate roughly doubles with every 10°C temperature rise.

Gas dilution

Dissolved gas such as natural gas and propane reduces oil viscosity and accelerates oil oxidation and deterioration.

Moisture content

PAG oil is highly hygroscopic. Excessive moisture causes hydrolysis and sharp rise of acid value.

Contamination and solid particles

Dust and metal debris accelerate wear and oil oxidation, greatly shortening oil life.

Incompatible oil mixing

Mixing PAG oil with mineral oil or PAO oil will cause sediment and rapid deterioration, even in small amounts.

3. Oil replacement criteria

Replace the oil immediately if any of the following occurs:

Total Acid Number (TAN) increases by more than 1.0 mgKOH/g compared with new oil

Viscosity at 40°C changes beyond ±15%

Water content exceeds 200 ppm (＜100 ppm for refrigeration systems)

Obvious darkening, turbidity, peculiar smell or sludge formation

4. Summary

Clean, low-temperature and low-dilution working conditions: 3–5 years / 8,000–12,000 hours.

Continuous high temperature, heavy gas dilution and corrosive environment: 1.5–3 years / 4,000–6,000 hours.