Saybolt Universal Seconds are a unit used to measure which property of oil?

• A. Viscosity
• B. Density
• C. Flash Point
• D. Pour Point

Answer: (A)

Viscosity is how thick or thin a liquid is and how strongly it resists flowing. Saybolt Universal Seconds measure that property by timing how long a fixed amount of oil takes to flow through a calibrated capillary in a Saybolt viscometer at a specific temperature. The result, in seconds, corresponds to how viscous the oil is: longer times mean thicker, slower-flowing oil, while shorter times mean thinner, faster-flowing oil. This unit is widely used in the petroleum industry because it provides a practical, comparable way to gauge flow behavior for oils and other hydrocarbons, and it can be related to standard viscosity values if needed. It’s not about density, which is mass per volume; nor about flash point, the temperature at which vapor can ignite; nor about pour point, the lowest temperature at which oil will still flow.