What is the standard unit of measurement for fuel additives?

The standard unit of measurement for fuel additives is parts per million (ppm) because this unit effectively expresses very small concentrations of substances, such as additives, in larger quantities of fuel. Fuel additives are used in minute quantities relative to the total amount of fuel and therefore require a measurement unit that can represent such small proportions. Ppm allows for precise dosage and effectiveness evaluation of the additives, ensuring they can improve fuel performance without adverse effects.

In comparison, gallons and liters are typical units for measuring larger quantities of liquids, such as fuel itself, rather than its additives. Milliliters, while useful for measuring smaller volumes than liters or gallons, still do not provide the granularity needed for the extremely small ratios often involved with fuel additives. Therefore, ppm is the most appropriate and standardized measurement for this purpose.