If the main oil filter is clogged, what component allows unfiltered oil to lubricate the engine?

The filter bypass valve plays a crucial role in the engine's lubrication system when the main oil filter becomes clogged. Its primary function is to ensure that oil continues to flow to the engine even if the filter is unable to allow oil to pass through due to excessive contamination or blockage.

When the filter is clogged, the pressure differential across the filter increases. The filter bypass valve detects this situation and opens, allowing unfiltered oil to circulate through the engine. This ensures that the engine receives the necessary lubrication to function, albeit with the understanding that the oil is not being filtered, which could lead to increased wear and potential damage over time.

Other components, like the oil pump, are responsible for moving oil through the engine, but they do not specifically handle the issue of a clogged filter. The oil reservoir simply holds the oil, while the cooler bypass valve regulates oil flow through the cooler, which is unrelated to the filter's bypass functionality. Thus, the filter bypass valve is the correct answer, as it allows unfiltered oil to reach the engine when needed.