Question 83Motor Plants - 1st Asst/Chief

The correct answer is C) corrosive by-products are usually formed. Explanation: Excessive lube oil temperature in a diesel engine can lead to oil oxidation, which results in the formation of corrosive by-products. These corrosive compounds can damage engine components, accelerating wear and causing potential engine failure. This is the primary reason why oil oxidation due to high lube oil temperature is harmful to a diesel engine. The other answer options are incorrect because: A) lube oil viscosity may decrease or increase depending on the degree of oxidation, B) oil foaming is a separate issue not directly related to the harm caused by oxidation, and D) large oil consumption is a symptom of the problem, not the root cause of the harm.