I seem to recall it was a 25% kerosene/75% #2 blend that we used. However it was supplied to us ready-blended by our fuel company. so I would not guarantee those numbers 100%. We were using the fuel when the ambient temperature consistently went below -10C (14F).
Honestly my preference (although it's more expensive) is for using a properly refined #1 diesel fuel rather than a blend of 2 existing products. The reason for this is that to produce a #1 diesel fuel the fuel company removes a large part of the wax products from a #2 diesel fuel, whereas adding kerosene only removes the wax from the pecentage of #2 diesel fuel in the blend that is replaced by the kerosene. All this afrects the "Cloud Point" of the fuel. See below for a long-winded explanation ........
Cloud Point - It is important to understand that the cloud point of a fuel is different from the pour point. There is no relationship between cloud point and the pour point. The cloud point is the temperature that allows some of the heavier components in the wax to solidify in the fuel. This wax is not a contaminant in the fuel. The wax is an important element of No. 2 diesel fuel. The wax has a high fuel energy content and the wax has a very high cetane value. Removal of the heavier wax lowers the cloud point of the fuel and also reduces the amount of energy that can be obtained from the fuel. Removal of the wax also increases the cost because less fuel can be made from the same amount of crude oil. The cloud point of the fuel is important because the cloud point can limit the performance of the fuel filter. The wax will alter the fuel characteristics in cold weather. Solid wax can fill the fuel filters and will stop the flow of fuel.
You can lower the cloud point of a diesel fuel by mixing it with a different fuel that has a lower cloud point. No. 1 diesel fuel or kerosene may be used to lower the cloud point of a diesel fuel. The efficiency of this method is not good, because the ratio of the mixture does not have a direct relation to the improvement in cloud point. The amount of fuel with low cloud point that is required makes the process less preferable to use. The following illustration contains a table that can be used to find the necessary mixture for two fuels with different cloud points. In order to use the table, you must know the exact fuel cloud point of each fuel. This specification can change from one purchase of fuel to the next purchase of fuel. This specification is normally available from personnel at the source of the fuel supply. When fuels that have a lower cloud point are not available, this method cannot be used.
Here's how to read the chart. Find out the cloud point of the 2 fuels you plan to use in your blend. Draw a line from one to the other - Line A. Take the % of lighter fuel in the blend from the scale at the bottom of the chart and draw a vertical line (Line B) up until it hits line A. From the point where the 2 lines hit one another read horizontally to your left - Line C. This is the Cloud Point of your blend.