Lubricant suppliers such as ExxonMobil do not recommend use of their lubricants beyond the stated shelf life. But for the average user, identifying an expired lubricant may not be as easy as it is with something such as food, where “best used by” dates are prominently displayed, and rotten food is pretty obvious. Knowing a little about lubricants can help users determine if lubricants are OK to use or should be recycled.

For lubricants, the rule of thumb when it comes to shelf life is five years. If the seal on the container is broken the five-year rule goes out the window and it’s takes an experienced person to tell if something is fit for use. Most lubricant manufacturers will say that when it comes to a container with a broken seal, assume the lubricant is past its shelf life.

Some easy ways to determine if an industrial or automotive lubricant is past its shelf life include:

• Cloudy appearance or strong, unnatural odor

• Significant sediment buildup (some sediment buildup is natural)

Things to look for regarding greases include:

• Excessive oil separation (a little is normal)

• Change in consistency

• Unnatural color or odor

• Change in texture

One thing to note regarding greases – oil naturally separates from most grease and storage temperatures in excess of 110 Fahrenheit can accelerate separation. Ideal storage temperature is between 32 and 75 Fahrenheit. For water-based lubricants such as metalworking coolants refer to above, and also look for:

• Separation of oil and water

• Bulging containers

Other lubricants, such as moisture-sensitive ones, or those with high-additive content, may exhibit phase separation, heavy sediment drop out or a hazy appearance.

To optimize shelf life, always store lubricants in a dry, temperature-stable environment. Any excessively hot or cold storage periods could affect shelf life. Heat increases the rate of oil oxidation which can affect viscosity and deposit formation and cold temperatures can lead to wax and sediment problems. Expansion and contraction due to fluctuating temperatures can lead to atmospheric contamination. Some things to know regarding lubricant storage include:

• Light can change the appearance and/or color of lubricants, always store in sealed, opaque containers

• Water intrusion can promote microbial growth and affect some additives, forming an insoluble substance

• Never store in an environment that is dusty or dirty

• Oxygen and carbon dioxide will affect viscosity – keep containers sealed from the atmosphere

Proper inventory management will insure you are maximizing your lubricant investment.