ISO VG ↔ SAE Viscosity Grade
Approximate mapping between ISO VG grade numbers (viscosity at 40 °C) and SAE J300 engine-oil / gear-oil grades.
SAE grade (approx)
SAE 30 / 20W-50
ISO VG (approx)
- -
Formula, assumptions, and limits
ISO VG = kinematic viscosity mid-point at 40 °C. SAE J300 grades based on viscosity at 100 °C for mono-grades and 150 °C HTHS for multigrades - so the mapping is approximate. For critical applications check the actual KV-40 vs KV-100 pair from the PDS.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| ISO viscosity grade | cSt at 40 °C | ISO 3448 | |
| SAE J300 grade number | - | SAE J300 |