What would a cracked valve cover gasket likely lead to?

A cracked valve cover gasket typically results in oil leaks. The valve cover gasket is designed to create a seal between the valve cover and the engine block, preventing engine oil from leaking out. When the gasket cracks, it can no longer maintain this seal effectively. This leads to oil escaping, which can create various problems such as lower oil levels, potential engine damage due to lack of lubrication, and even oil pooling in areas that can impact other components.

In contrast, the other options (increased power output, improved fuel efficiency, and enhanced engine longevity) are outcomes that are unlikely to be associated with a defective gasket. A deteriorating gasket would not contribute positively to engine performance or efficiency; instead, the oil loss it causes may lead to the opposite—reduced power output and engine issues over time.