Flypast,

If you're ever unsure of your diesel fuel %'s here's a method that'll show exactly what your fuel is.

Place 100ml of your current fuel into a measuring beaker and allow to sit open to the air, but not any possible rain or falling impurities. On a warm day it should only need overnight and when you next check, the ether should have evaporated off and the remaining components will have separated.

You will be able to see the kero and oil as separate components and measure their volumes. Giving Xml Kero, Yml Castor, and the part that would make up 100ml will be the missing ether.
From that you can determine if your fuel had lost ether and the necessary adjustment can be made.

This may take longer in colder climates.