How does an oil acid test kit indicate the presence of acid?

• A. By a color change
• B. By a metallic smell
• C. By a pH meter reading
• D. By a change in viscosity

Answer: (A)

An oil acid test kit detects acidity through a colorimetric indicator. When the oil sample interacts with the reagent, the acids present cause a chemical reaction that changes the dye’s color. That visible color shift is then compared to a reference chart to determine whether acid is present and roughly how strong it is. This simple color change approach is quick and practical for field testing, unlike relying on a smell, a pH meter, or changes in viscosity.