Question

determination of viscosities of different lubricating oils of different brands

Answer 1

Viscosity  of different oils can be measured using different different method. But remember the temperature is the important factor in this as the temperature is the important factor which determine the viscosity. 
In the Laboratory

1) capillary  Tube viscometers are used which includes the measurement of viscosity under the gravity action and flow rate . Oil sample placed in U-tube and allow to flow freely and time of flow , flow rate , is noted which determined the viscosity 

2) Rotary viscometer:

These are digital viscometer used mostly in the laboratory to measure as they easily measure the viscosity .  Oil sample can be placed in a glass and which placed under a metal spindle which rpm is fixed . The viscometer operate on automatic system and measure the viscosity directly and display the reading in Centipoise(cP) 

Answer 2

determination of mass percentage of oil from different brands