ASTM D2270
Viscosity Index
Calculate the third parameter when you know two of three: ν₄₀, ν₁₀₀ and VI. Based on ASTM D2270.
Viscosity index calculator
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e.g. 46, 68, 100, 220…
e.g. 6.8, 8.5, 11.5…
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ASTM D2270 formulas: H(ν₁₀₀) = 0.1684·ν₁₀₀² + 11.85·ν₁₀₀ − 97 · L(ν₁₀₀) = 0.8353·ν₁₀₀² + 14.67·ν₁₀₀ − 216 · VI = (L − ν₄₀) / (L − H) × 100. ν₁₀₀ calculated by numerical bisection.
Reference: classification by VI
The viscosity index indicates the oil's sensitivity to temperature changes
| VI Range | Classification | API Group |
|---|---|---|
| < 80 | Conventional mineral oil | Group I |
| 80 – 120 | Refined mineral oil | Group II–III |
| 120 – 140 | Synthetic base or HVI | Group III / IV |
| > 140 | Premium synthetic base (PAO, ester) | Group IV–V |
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