What is a possible consequence of over-filling the engine with oil?

Over-filling an engine with oil can lead to several serious issues, with one significant consequence being damage to the catalytic converter. When there is too much oil, it can froth and create pressure within the crankcase, leading to oil being forced into parts of the engine where it shouldn't go. This can result in oil entering the combustion chamber, where it burns along with the fuel. The burning oil generates excess pollutants, which can overwhelm the catalytic converter, a component designed to reduce harmful emissions. This can cause the converter to fail, leading to costly repairs and negatively impacting vehicle emissions.

On the other hand, the other options suggest beneficial outcomes that misrepresent the effects of over-filling oil. Improved engine performance and increased fuel efficiency are not achievable through over-filling; in fact, these aspects may deteriorate due to related complications. Similarly, extended engine life is unlikely, as the stress and damage caused by excess oil would lead to premature failure of engine components. Understanding the implications of proper oil levels is crucial for maintaining vehicle performance and longevity.