The shelf life of an industrial grease is a major factor to consider in proper inventory management to guarantee its suitability for use and its ability to deliver the desired performance in the applications for which it was designed. Shelf life can mean many things. Here, we are primarily talking about the time period in which a stored lubricating grease can be used without quality-control checks to confirm performance attributes.
In general, the estimated shelf life of most greases is two to five years from the date of manufacture, given the greases have been properly stored in their original containers and are unopened. Opinions about the overall shelf life of grease (how long it’s usable at all) vary. Obviously, it is desirable to get the most amount of shelf life from your grease while maintaining its performance characteristics. Here are some useful tips to help you maximize the life of your industrial grease.
Storage and Handling are Paramount
Most grease goes bad not because of a chemical/composition problem, but because of contamination. And how is contamination caused? From open containers. Dust and debris and even air (oxygen, CO2) can cause contamination in open containers. If your container has been opened and closed a lot (or left open all the time), the risk of contamination’s effect on the grease’s properties is far greater.
The effects of water and light and even atmospheric conditions (like temperature extremes) that can react with lubricants, affecting their viscosity and consistency, also need to be considered. So you’ll want to keep your grease out of extreme conditions as much as possible. In addition, the grease’s properties can change over time, depending on the type and concentration of the thickener used, the base, and other additives in the grease. You’ll also want to refer to your grease’s SDS for specific storage instructions.
Some users prefer to buy grease in tubes, or if in tubs, they transfer a small amount to a piece of scrap paper or foil, use what is needed. Otherwise their efforts to repack bearings or other parts in clean room conditions will be for naught. (If the grease is in a tube, there is less room for oxygen or debris to enter/contaminate it.)
A natural occurrence in most greases over time, oil separation can be accelerated by high temperature environments. Therefore, we recommend storing industrial greases in a cool, dry, indoor area where airborne particles are minimal.
Other factors to keep in mind to extend the shelf life of grease include:
- Inventory rotation—use the oldest containers first.
- If grease must be stored outside, make sure it is covered and away from sources of water.
- Make sure grease containers are stored upright to avoid formation of air bubbles from settling and shifting grease—making it more difficult to pump through a gun. Grease guns should be shored with the tips upright to avoid gravity forcing the oil to separate from the thickener.
To summarize, keeping the containers sealed as much as possible; storing the grease in a cool, dry place; storing containers indoors and upright; rotating your inventory to use the older grease containers first; minimizing airborne contaminants and exposure to water; and the other tips mentioned above can help maximize the shelf life of your industrial grease.