Lots of information here, but to directly ask your question: You need the density of 4 liquids, and you want to calculate the density. You can do that, once you make some measurements, or maybe you have an instrument that can determine it for you. There may be tables to correct for the temperature, or you may want to make the determination at or near 100 C.
I am not a chemical engineer, but it sounds to me like the viscosity is just as important as the density for your particular application. So you may well need an instrument to measure that, as well..