Why is my lubricating grease separating?
First and foremost this article has nothing to do with the John Travolta or Olivia Newton-John – there are plenty of online blogs that discuss this movie relationship in detail.
So you are opening a jar, can, tube or pail of grease and getting ready to slather it on your favorite piece of machinery and all of sudden you realize that there is some oil bleeding on the surface. You ask yourself – what’s happening here? Did I get bad product from my supplier? Is this grease too old? On that note, did I grease this unit on its last required interval? Will this grease impact my machinery?
What is happening to my grease?
When grease is packaged, it is usually compressed with some sort of plunger mechanism to avoid air pockets and to ensure a level surface. On occasion packaged grease may have an air bubble in the packaging. More common though is that you have used the grease at least once already and the surface of the grease is no longer smooth and flat (i.e. it has high and low spots).
When an air bubble or a depression in the surface of the grease occurs, you get an osmotic pressure imbalance and the oil component of the grease will leach into the open cavity. The rate at which this bleeding will occur is a factor of the grease composition, temperature variations and vibrations. Dave Pinchuk of Thermal-Lube explains this phenomenon: “Just think of digging a hole in the sand next to the ocean. Water will eventually fill the hole. This is what is happening to your grease.”
Can I still use the grease effectively?
Yes. Usually the amount of oil you see in the container is only a fraction of the total grease and will negligibly effect the performance. Try stirring the grease manually. If the grease re-absorbs the oil – you are good to go.
What can I do to prevent the grease from separating or bleeding?
First, when you’re finished greasing, level the grease surface before placing the container back in storage.
Second, try to store your greases away from heat and cold sources or in areas where temperature fluctuations are common.
Photo Credit: U.S. Naval Forces Central Command under the Creative Commons License