The information about grease on the following link is informative
Grease Analysis - Monitoring Grease Servicability and Bearing Condition
By Bill Herguth, Herguth Laboratories
Viscosity of Grease
"The viscosity of grease is often misunderstood. The viscosity
typically listed on a new oil data sheet is usually the
kinematic viscosity of the oil used in blending the grease
measured, using the standard ASTM D445 method. The kinematic
viscosity of the base oil is important in ensuring the correct
grease, containing the correct grade of oil is used for
lubrication purposes. However, we can also measure the viscosity
of the grease itself. Since a grease is non-Newtonian, we can
only measure the apparent viscosity because the viscosity of a
non-Newtonian fluid changes with shear stress see “Understanding
Absolute and Kinematic Viscosity” by Drew Troyer). The apparent
viscosity of a grease is determined using ASTM D1092. This test
measures the force required to force the grease through an
orifice under pressure. As such, this test is an ideal way of
determining the flow characteristics of grease through pipes,
lines, dispensing equipment as well as its pumpability."
"Rheology measurements of grease may soon replace both the cone
penetration and the apparent viscosity measurements. Rheology is
the study of the deformation and/or flow of matter when it is
subjected to strain, temperature and time. A rheometer only
requires a few grams of sample to perform the analysis, yielding
much more information than the cone penetration or the apparent
viscosity measurements. This makes the rheology measurement an
ideal test for small amounts of used grease."