In order to calculate the viscosity index of a lubricant, apparently you need two input parameters. The kinematic viscosity (mm²/s) at 40°C and at 100°C.
If I got it right, mm²/s means the distance in square millimeters a fluid can travel through a capillary within the timeframe of a second.
Usually, most materials are "more fluid" when heated, which should imply that the viscosity will be lower, the higher the temperature. As far as I know viscosity is the opposite of fluidity => honey is more viscous than water.
So this is my assumption:
- More mm²/s traveled = Lower Viscosity
- Less mm²/s traveled = Higher Viscosity
But now, everywhere I looked online (see e.G. links below), the input value of V40 has to be higher than V100.
Does that mean oil can travel less distances through a capillary when it's hotter?
Please be so kind to explain in layman terms as I'm not too well versed in the field of natural sciences