Where the VG number comes from
The ISO VG grading system (ISO 3448) measures an oil's kinematic viscosity at a 40°C reference temperature, in centistokes (cSt), and rounds it to the nearest standard number from a fixed table. That means VG 46 indicates the oil's viscosity at 40°C is close to 46 cSt.
Why this global standard matters
The ISO VG standard lets engineers and operators compare and substitute oils of similar viscosity regardless of brand or manufacturer. This is the same underlying system MAADANOL's Equivalent Product Finder uses to compare against other brands like Shell or Mobil.
Why choosing the wrong grade is costly
Using a grade lower than needed thins the lubricating film and causes premature wear; a grade higher than needed increases flow resistance and reduces system energy efficiency. Always base your choice on the equipment manufacturer's recommended grade, not an estimate or habit.
Key Takeaways
- The VG number indicates oil viscosity at the 40°C reference temperature
- The global ISO VG standard enables comparison across different brands
- Always base grade selection on the equipment manufacturer's recommendation
