The ___ the viscosity index, the lesser the change in viscosity as the temperature varies.

The ___ the viscosity index, the lesser the change in viscosity as the temperature varies.

• A. Higher
• B. Lower
• C. Constant
• D. Unknown

Answer: (A)

The main idea is that viscosity index measures how sensitive an oil’s viscosity is to temperature changes. The higher the viscosity index, the more stable the oil’s viscosity is across a range of temperatures, so the change in viscosity with temperature is smaller. That’s why the statement is best understood as: higher viscosity index means lesser viscosity change when temperature varies. A lower VI would mean the viscosity changes more with temperature, while a constant or unknown VI doesn’t describe the temperature-viscosity relationship as defined.