What is the formula to determine the factor of dirtiness between two sets of ISO codes for oil samples?

The formula for determining the factor of dirtiness between two sets of ISO codes for oil samples is based on a mathematical representation of the differences in cleanliness. The correct choice involves using an exponential function, specifically raising 2 to the power of the difference in ISO cleanliness codes.

Each ISO cleanliness code represents a level of contamination, with each step representing a doubling or halving of particle counts. When you have a difference quantified by two ISO codes, the factor of dirtiness is computed as an exponential function to accurately capture this multiplicative change in contamination levels. Therefore, utilizing an exponential base of 2 aligns with how cleanliness levels are defined, where every unit of difference in the ISO code reflects a substantial change in the number of contaminants present in the oil sample.

This understanding ensures that the calculation effectively reflects the significant impact of even a small numerical difference in ISO cleanliness codes, directly correlating with contamination levels.