Recommended ISO Viscosity Grades of Oil for Bearings.

🛢️ Recommended ISO Viscosity Grades of Oil for Bearings

Proper lubrication is critical for the reliability, efficiency, and longevity of bearings in pumps, motors, compressors, and other rotating machinery. Choosing the correct ISO viscosity grade of oil based on operating temperature and bearing type ensures smooth operation, reduces wear, and prevents premature failure.   This Blog provides recommended viscosity grades for ball bearings, cylindrical roller bearings, and other roller bearings at different operating temperatures.

🔹 Importance of Correct Oil Viscosity

- Lubrication Efficiency: Oil viscosity determines the thickness of the lubricating film between bearing surfaces.  

- Wear Protection: Correct viscosity prevents metal‑to‑metal contact, reducing friction and wear.  

- Temperature Control: Proper oil selection helps dissipate heat and maintain stable operating conditions.  

- Energy Savings: Overly thick oil increases drag and power consumption, while too thin oil fails to protect bearings.  

- Selecting the right ISO viscosity grade is essential for bearing reliability and energy efficiency.

🔹 Recommended ISO Viscosity Grades for Bearings

🔹 Explanation of Recommendations

- Ball & Cylindrical Roller Bearings: Require lower viscosity oils compared to other roller bearings due to their design and lower frictional resistance.  

- Other Roller Bearings: Need higher viscosity grades to maintain adequate film thickness under heavier loads.  

- Temperature Effect: As operating temperature increases, oil viscosity decreases. Therefore, higher viscosity grades are recommended at higher temperatures to maintain lubrication effectiveness.  

🔹 Practical Tips for Bearing Lubrication

- Always follow manufacturer’s recommendations for oil grade and lubrication intervals.  

- Monitor bearing operating temperature regularly to ensure correct oil selection.  

- Use oil analysis to check for contamination, oxidation, or viscosity breakdown.  

- Avoid mixing different viscosity grades, as this can compromise lubrication performance.  

- Ensure proper storage and handling of lubricants to prevent moisture or dust contamination.  

🔹 Key Takeaways

- Correct ISO viscosity grade selection is vital for bearing performance and reliability.  

- At 70 °C, use VG 46 for ball/cylindrical roller bearings and VG 68 for other roller bearings.  

- At 80 °C, use VG 68 and VG 100 respectively.  

- At 90 °C, use VG 100 and VG 150 respectively.  

- Proper lubrication reduces wear, power losses, and premature failures.