Hi Davidkien68, welcome here!
For the density, you could add the masse of all constituents, and the volumes of gaseous butanol and water plus the volume of liquid Diesel oil, in a first approximation. All at normal pressure?
Or more subtle, compute the vapour pressure of your Diesel oil (very variable at 176°C, whether this oil boils at 250°C or 350°C), for instance by Antoine's equation if you know the parameters for the current oil, and add the volumes of the liquid part to the volumes of all gases.
The viscosity is unclear to me. By googling
I got half a million hits, among othershttp://aaqr.org/VOL2_No1_June2002/8_AAQR-02-06-OA-0008_71-86.pdf
other documents may be more directly useable.