When should a bearing lubrication review consider oil rather than grease?

LILY Bearing | 2026-10-28

Best answer

Choose a system for the actual operating duty

Grease can simplify lubricant retention and the surrounding equipment, while oil systems can provide functions such as circulation, filtration and cooling when designed for them.

NSK distinguishes several oil-delivery methods rather than treating oil lubrication as one uniform arrangement. The choice therefore depends on the bearing duty, operating temperature, speed, contamination conditions and maintenance capabilities. Replacing grease with oil is not simply substituting one material in the same empty space: the assembly may need a different supply, return and sealing design. Equally, a self-contained grease arrangement may be appropriate where those additional oil-system functions are unnecessary.

Compare the required functions before comparing products

Create a checklist for delivery reliability, lubricant retention, heat removal, contamination control, access and maintenance responsibilities.

For a proposed circulating-oil system, identify the supply, return, filter and cooling provisions actually included in the design. For a grease system, identify how the required quantity reaches the bearing and how replenishment or replacement is managed. Do not award a benefit merely because a lubricant type could provide it in some other system. A documented comparison shows which required functions each proposed arrangement establishes and which remain unresolved. The final selection still needs the exact equipment and bearing requirements rather than a general claim that one lubricant category extends life in every machine.