The A.P.I. (American Petroleum Institute) takes data from automobile manufacturers and determines what qualities motor oils must have to properly lubricate engines. Oil companies use this information to blend additives into petroleum base stocks to produce proper motor oils used in automotive engines The S.A.E. (Society of Automotive Engineers) oversees testing and sets standards for oil viscosities. On oil containers or labels the weight is noted as “SAE 10w30” (usually noted within or near the API Donut), meaning that in accordance with Society of Automotive Engineer standards, the viscosity of the product is a 10-weight in colder temperatures and a 30-weight in warmer temperatures. Note that the “w” between the 10 and 30 stands for “winter” (or colder). The “w” is included in all multi-grade oil labels as a sign that the first number is the cold viscosity measurement, while the second number is the warm viscosity measurement. With regard to tools, SAE refers to fractional measuremen