Which of the following is NOT considered a contaminant?

Lubricants are not considered contaminants because they serve a specific purpose in machinery and equipment, helping to reduce friction and wear. They are engineered products designed to perform within the parameters of various mechanical systems, ensuring efficient, smooth operation. In contrast, water, microbiological growth, and sediments can negatively impact fuel quality and performance by introducing elements that disrupt combustion processes or contribute to engine wear. Water can promote corrosion, microbiological growth can lead to the formation of sludge and block filters, and sediments can cause fuel system failures. Thus, lubricants are distinct in their intended function rather than being undesirable materials that compromise fuel integrity.