Yes. Actually, most XL7s are used with non-Newtonian fluids. The resonant technique creates a high shear rate and this has the advantage of forcing the viscosity measurement to a relatively flat part of the viscosity/shear rate curve.
The result is that high repeatability is maintained even where a fluid shows dramatic non-Newtonian characteristics, such as polymer melts and gels.
For further information see help section: Getting Started > Non-Newtonian fluids