OptiMVD measures viscosity according to ASTM D7945. This method is based upon the Hagen-Poiseuille principle of capillary flow. To determine viscosity with OptiMVD, a sample is drawn from a capped sample vial and then introduced into the measuring cell at a controlled, specified temperature. The measuring cell contains a horizontal capillary tube with optical sensors. A thermal block surrounds the measuring cell. Density is determined by ASTM D7777 method. The OptiMVD measures density at multiple temperatures yielding precision that is much better than other D7777 density meters.