The compatibility of greases and oils: A critical factor for maintenance

Many technicians assume that "grease is just grease" and "oil is just oil", but in reality, the situation is far more complex. Every year, thousands of machines fail due to the mixing of incompatible lubricants.

In this article, we explain why lubricant compatibility is crucial, the risks of mixing lubricants, and how to prevent issues when transitioning to a new lubricant.

Understanding lubricant composition

To better understand what happens when incompatible lubricants are mixed, it is important to first explain their composition.

A lubricating oil consists of:

• Base oil – Provides the lubricating function.
• Additives – Enhance or strengthen the properties of the base oil.

A grease is a lubricating oil with a thickener added. The thickener itself does not provide lubrication; its primary function is to retain the oil and keep it in place at the lubrication point.

What happens when incompatible lubricants are mixed?

When incompatible lubricants are combined, severe problems can arise:

1. Thickener incompatibility
   Mixing incompatible greases can cause the thickener to release the oil, a phenomenon known as oil bleeding. This results in a gum-like substance that lacks lubricating properties, leading to premature wear and failure.
2. Viscosity changes
   Viscosity is one of the most critical factors in lubricant selection. Mixing oils with different viscosities disrupts the balance, making lubrication less effective and increasing mechanical stress.
3. Separation and leakage
   Some types of base oils are completely incompatible with each other. This can lead to oil separation, seal degradation, and leaks, significantly reducing the lubricant’s effectiveness.
4. Additive interaction
   Additive packages are precisely formulated to enhance base oil properties and counteract undesirable effects. Mixing different additive packages can neutralise their effectiveness, resulting in reduced protection and increased wear.

How to identify lubricant contamination?

Detecting lubricant contamination is not always straightforward, but several indicators can help:

• Greases – Look for oil bleeding beneath bearings or hardened grease inside bearing housings.
• Oils – Check for visible fluid separation and potential leaks.
  Increased Operating Temperature – A rise in machine temperature may indicate contamination with an incompatible lubricant.
• Oil or grease analysis – Laboratory analysis can confirm contamination (a baseline measurement is necessary for reliable results).

What to do if lubricants have been mixed?

If you suspect that incompatible lubricants have been combined, follow these key steps:

1. Shut down the machine – Prevent further damage by stopping the system immediately.
2. Check the documentation – Verify the specifications of the recommended lubricant.
3. Clean the lubrication system – Remove the old, contaminated lubricant. Flushing with a compatible cleaning oil may be necessary.
4. Apply the correct lubricant – Refill the system with the appropriate lubricant.
5. Monitor performance – Regularly check the machine after lubrication to ensure proper functionality.

Conclusion

The compatibility of greases and oils is a critical aspect of effective lubrication management. Mixing incompatible products can lead to severe machine failures and costly repairs, particularly in food processing environments, where food safety regulations must be met.

By following the guidelines outlined in this article and using the correct lubricants, you can extend the service life of your equipment and maintain optimal machine performance.

📥 Want to learn more about the compatibility of Interflon oils and greases? 

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Unsure whether your lubricants are compatible? Let an expert review your situation to prevent unnecessary damage. Contact us today!