A Saybolt viscosimeter is primarily used for what purpose?

A Saybolt viscosimeter is primarily used for testing and grading oils, which is critical in determining their flow characteristics at specific temperatures. This instrument measures the time it takes for a specific volume of oil to flow through a calibrated orifice under defined conditions. The results help in assessing the viscosity of the oil, which is a vital property that influences the oil's performance in various applications, such as lubrication and fuel efficiency. Different grades of oils correspond to different viscosities, and understanding these characteristics is essential for selecting the appropriate oils for engines and machinery. Therefore, the use of a Saybolt viscosimeter in this context is crucial for ensuring that the right type of oil is used for optimal performance.