What the cetane number is
For diesel, the counterpart of the octane number is the cetane number: it shows how quickly diesel ignites after injection. A higher cetane number means easier cold starts and smoother combustion.
When it makes sense
- In winter, when cold starts are harder.
- In modern engines, to keep the injectors clean.
- As an occasional tank between fill-ups with standard diesel.
The extra cost
For 50 litres, the difference is about 43.00 RON per fill-up at today's average prices.