Question 146Motor Plants - QMED

The correct answer is B) form a protective film on metal surfaces. Corrosion inhibitors and/or soluble oils are added to diesel engine cooling systems to form a protective film on the metal surfaces of the cooling system. This helps prevent corrosion and wear of the metal components, which is essential for maintaining the integrity and longevity of the cooling system. The other answer choices are incorrect because: A) increasing cooling water hardness is not the purpose of corrosion inhibitors, C) reducing the cooling water temperature is not their function, and D) maintaining low pH in the cooling water is not their primary role.