Turbine meters have been used for the custody transfer of refined petroleum products and light crude oils for over 40 years. When correctly applied, they offer high accuracy and long service life over a wide range of products and operating conditions. Traditionally turbine metes were used for the measurement of low viscosity liquids and PD meters for higher viscosities. However, new developments in turbine meter technology are pushing these application limits while increasing reliability and accuracy. This paper will examine the fundamental principles of turbine meter measurement as well as new developments including: smart preamps for real-time diagnostics, helical flow turbine meters for higher viscosity applications, higher performance flow conditioners to increase accuracy, and viscosity compensation to extend the application limits.