Why are two ratings used to obtain the pump rating?
The correct name for the (RON+MON)/2 formula is the “antiknock index”, and it remains the most important quality criteria for motorists [25]. The initial octane method developed in the 1920s was the Motor Octane method and, over several decades, a large number of octane test methods appeared. These were variations to either the engine design, or the specified operating conditions [65]. During the 1950-1960s attempts were made to internationally standardise and reduce the number of Octane Rating test procedures. During the late 1930s – mid 1960s, the Research method became the important rating because it more closely represented the octane requirements of the motorist using the fuels/vehicles/roads then available. In the late 1960s German automakers discovered their engines were destroying themselves on long Autobahn runs, even though the Research Octane was within specification. They discovered that either the MON or the Sensitivity ( the numerical difference between the RON and MON nu
