One of the physical properties of fuels that is relevant to use in a combustion engine is viscosity. the viscosities of diesel, biodiesel, and vegetable oil are very different from each other. why is viscosity an important property in this context? how does the viscosity of diesel compare to the viscosity of biodiesel? (hint: check out the "additional reading" links in last week's introduction section) why is the viscosity of biodiesel lower than the viscosity of vegetable oil?