A linear bearing is a precision instrument, but without the proper thin film of lubricant, it is just metal grinding on metal. Lubrication serves three critical roles: reducing friction, dissipating heat, and preventing oxidation.

However, the debate between Grease and Oil isn't about which is "better"—it's about which is right for your specific environment.

1. Grease Lubrication: The "Set and Forget" Choice

Grease is essentially oil held in a "sponge" of thickener (soap). It is the standard for 90% of industrial linear motion applications.

• The Advantage: It stays where you put it. Because of its viscosity, it doesn't leak out of the carriage easily, making it ideal for vertical axes.

• Protection: Grease acts as an additional seal, helping to keep dust and contaminants away from the internal recirculating balls.

• Maintenance: Longer intervals between "re-greasing" cycles compared to oil.

• Best For: Standard factory automation, vertical Z-axes, and environments where oil leakage would contaminate the product (like food packaging).

2. Oil Lubrication: The High-Performance Choice

Oil is a liquid lubricant that must be constantly or periodically replenished, often through a centralized piping system.

• The Advantage: Heat dissipation. In high-speed applications (>2 m/s), grease can churn and generate heat. Oil flows, carrying heat away from the ball screw and nut.

• Cleaning Effect: As oil flows through the carriage, it "flushes" out microscopic wear particles and contaminants.

• The Downside: It’s messy. Oil tends to pool at the bottom of the machine and requires a complex system of pumps, timers, and catch-pans.

• Best For: High-speed CNC machining centers, 24/7 continuous production lines, and high-temperature environments.

3. Comparing the Characteristics

The "Vertical Axis" Warning

If you are using a TOCO linear module in a vertical orientation, grease is almost always the better choice.

If you use oil, gravity will pull the lubricant to the bottom of the rail, leaving the top bearings dry and prone to "pitting" and failure. If oil must be used vertically, the lubrication pulse must be frequent enough to counteract gravity.

TOCO Recommendation: The Lithium Base

For most TOCO products, we recommend a Lithium-based grease with "Extreme Pressure" (EP) additives.

This provides the best balance of film strength and longevity for standard industrial loads. In cleanroom environments, specialized "low-outgassing" greases must be used to prevent vacuum contamination.