Are saying that the castor is being burned in your engines? I'm confused at this point.

That thread is interesting but it's quite old. Now we have ultra low sulphur diesel which is supposed to have a higher CN. They never given the actual rating because law only requires a minimum. Many references said premium diesel would have 5 point high CN. There are so many references to No.1 diesel being the same a kerosene that there might not be much of a difference.

One thing that stands out in my mind is synthetic diesel fuel. I read a couple reports that said it has a CN of 70+. I have no idea where to get the stuff though.

Greg