Which of the following is NOT a likely symptom of lubrication issues in an engine?

In the context of lubrication issues within an engine, it's important to understand the typical symptoms that arise when the lubrication system is not functioning properly.

Typically, issues with lubrication can lead to increased engine noise due to insufficient oil causing improper lubrication of moving parts, which allows for increased friction and wear. This noise often indicates that the engine components are not being properly protected. Furthermore, overheating is a common symptom; engine oil not only lubricates but also helps to dissipate heat. When lubrication fails, it can result in excessive temperatures. Loss of power can also occur as lack of lubrication can hinder engine efficiency, leading to poor performance.

In contrast, increased fuel efficiency is not a symptom associated with lubrication issues. In fact, if an engine experiences lubrication failure, it usually results in reduced efficiency due to increased friction and potential damage to engine components, requiring more fuel to operate effectively. Thus, while the other options align with the common manifestations of lubrication problems, increased fuel efficiency stands out as the only symptom that would not be linked to lubrication issues.