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.

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.