What benefit does flushing the lubricating system provide for engine longevity?

Flushing the lubricating system primarily serves the purpose of removing sludge and deposits that accumulate over time due to oil breakdown and contaminants. These substances can hinder the performance of the engine by obstructing oil flow and reducing its effectiveness in lubricating critical components. When sludge builds up, it can lead to increased friction between moving parts, potentially causing overheating and accelerated wear. By performing a flush, these harmful materials are eliminated, allowing for better oil circulation and reducing the risk of engine damage. This contributes significantly to the overall longevity of the engine, as it minimizes the risk of mechanical issues that can arise from poor lubrication.

The other options, while related to engine operation, do not directly address the primary benefit of flushing the lubricating system. Increasing oil capacity is important for maintaining proper lubrication levels but doesn't relate to the flushing process specifically. Cleaner combustion and enhanced fuel efficiency are beneficial general results of proper engine maintenance but are not directly impacted by flushing the lubricating system. The key focus here is the removal of sludge and deposits, which is crucial for maintaining engine health.