Lubricating Bearings: Oil v.s. Grease

Lubrication is an ancient procedure of making machines last longer. Most engineers use lubricants to reduce friction and this procedure has improved over the years alongside technology. They serve a purpose in lubricating machinery such as bearings to provide optimal performance and minimal friction.

Some procedures involved in lubricating bearings are protecting surfaces from corrosion, sealing against contaminants, and serving as a barrier between sliding contact surfaces.

Oil or Grease?

Engineers use lubricants such as oil and grease in order to lubricate the bearings in machines. There has been a debate on which of two is the best lubricant to use. Oil and grease both have their strengths and weaknesses. In this article, you’ll learn which lubricant you should use.


Oil is the more popular option. It’s a general term for all oil lubricants. Natural mineral oil with additives or synthetic ones help prevent rust and oxidation; the former being the more common of the two.

Oil is much easy to pour. This serves as a convenient lubricant for car engines. However, oil collects bits of debris over time and must be replaced periodically. Replacing oil is much easier because it is less viscous than grease, which makes them easier to drain. Since oil flows freely, it enables it to carry away unwanted heat from the sliding surfaces. It helps reduce the risk of oxidation and additive depletion.



Grease, on the other hand, is a type of oil mixed with a thickening agent that turns into a semi-solid material.

Viscosity is important when determining which oil is needed for bearings. Viscosity refers to the fluid’s resistance to flow. Another term for it would be the gooeyness of a fluid. It gives a big contribution in the separation of rolling and sliding elements in a bearing. Hence, grease is the common to-go lubricant for bearings most of the time. The more viscous the grease is, the higher the chance for it to be contained inside a bearing envelope.

Grease is a better choice when dealing with sealed components that are hard to access. Over time, grease turns into a full liquid.

For your bearing needs, check out Bearings Direct. They’ll surely have the bearing you’re looking for!