Question 73Motor Plants - 1st Asst/Chief

The correct answer is D) a change in the oils viscosity. A 'Blotter test' is a simple field test performed on the lube oil of a diesel engine to determine if there has been a change in the oil's viscosity. This change in viscosity can indicate issues with the engine, such as contamination of the oil or excessive wear of engine components. The blotter test involves placing a drop of the oil on an absorbent material, like blotting paper, and observing how the oil spreads. This can provide a quick assessment of the oil's condition compared to new oil. The other answer choices are incorrect because they do not accurately describe the purpose of a blotter test. The flash point, specific gravity, and TBN (total base number) of the oil require more sophisticated laboratory testing and are not the focus of a basic blotter test.