Short answer
Sealed grease typically has 1–2 years shelf life; after opening, use within 6–12 months. Expired ≠ always failed, but risk increases significantly.
Grease shelf life by type
| Type | Sealed | After opening |
|---|---|---|
| General lithium | 2 years | 12 months |
| Synthetic | 3+ years | 18 months |
| Aluminum complex / polyurea | 2 years | 12 months |
| EP grease | 1.5 years | 6 months |
Manufacturer shelf life usually assumes sealed original packaging under proper storage.
Factors affecting shelf life
- Storage temperature: high heat accelerates oxidation, ideal 5–30°C;
- Air exposure: after opening, air ingress speeds oxidation;
- Contamination: water and dust break the gel structure;
- Base oil type: synthetics resist oxidation better, last longer.
Can you use expired grease?
Check 3 indicators:
| Indicator | Verdict |
|---|---|
| Appearance | > 10% oil separation, obvious color change, hard lumps → don't use |
| Smell | sour, burnt → don't use |
| Consistency | obviously softer or harder → don't use |
If all 3 are normal, downgrade usage (from critical equipment to general, emergency use). Don't use on critical applications.
How to extend shelf life
- Seal storage: tighten cap after opening;
- Avoid contamination: use clean tools;
- Cool, dark place: avoid direct sunlight;
- FIFO: use in production date order.
Conclusion
Shelf life is a reference, not a hard cut-off. Expired doesn't always mean bad, but risk is high. Don't use expired grease on critical equipment; downgrade usage is OK for non-critical.
Related reading
- 《What is Grease Oil Separation? Can You Still Use Separated Grease?》— separation is the most common sign of expiry.