BN of a mix of two cylinder oils (e.g., BN 70 + BN 140 topping-up): mass-weighted log-linear approximation.
Formula
$$ BN_\text{mix} = \frac{m_1 BN_1 + m_2 BN_2}{m_1 + m_2} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $BN$ | Base Number | mg KOH/g | ASTM D2896 |
| $m$ | Oil mass | kg | consumption log |
Sources
- ASTM D2896 - TBN.