Viscosity measurements are reported for a variety of systems as a function of shear using a thin film, double‐thermostatted, concentric cylinder viscometer. The basic instrument design and the cylinders which are of unusually narrow clearance and fine machining permit accurate and precise viscosity measurements to be made at homogeneous shear rates up to two millionsec.−1Measurements are reported on a molecular weight series of pure normal paraffin hydrocarbons fromn‐C8H18ton‐C32H66.Viscosities measured at the highest shear agree within a precision of 2% and better with known low shear hydrocarbon viscosities. This result indicates an absence of both heating effects and molecular degradation and reveals Newtonian flow over the entire103shear rate range of the instrument. Similar tests were also performed on several pure cyclic compounds in a test for conformational shifts between rotational isomers which possibly could be induced by a high shear field. The improved high shear concentric cylinder viscometer was also used to double the shear rate range for the established viscosity of standard API Oil 104, which is the most widely studied and the most non‐Newtonian of current non‐Newtonian viscosity standards.