I1SH135LAB Saybolt Chromometer The SH135LAB petroleum product Saybolt colorimeter is used to measure refined liquid petroleum products, such as undyed motor gasoline, aviation gasoline, jet fuel, naphtha, kerosene, and medicinal white oil. Saybolt color refers to the height of the liquid column measured when observed and compared with a standard color plate, which is closest to one of the three standard color plates. The Saybolt color number is specified as -16 (the darkest)