I am not an expert in rheology and I have some questions.

I have two different brands of viscometers, a Thermo Electron Viscotester E-L and a Brookfield DV-II+Pro. I can not get the same result with the LV-4 spindle on the Thermo device with the spindle no 64 on the Brookfield device. Theoretically, I know that these two spindles are the same geometry. (Am I wrong?)

In the Brookfield device manual say" When viscosity data must be compared, be sure to use the same test methodology: namely the same instrument, spindle, speed, container, temperature and test time.". One of the results is 30k while the other is around 70k. However, I did not expect a big difference between the two devices. The only thing that comes to my mind is that "Brookfield dsoes not recommend the use of these spindles (LV #4) to perform a calibration check on your instrument. Reasons pertain to the small amount of spindle surface that makes contact with the viscosity standard, the difficulty of establishing the immersion mark precisely and the need for precise temperature control at 25°C in the immediate vicinity of the spindle." mentioned in the device manual.

How do I know which result is correct?