Which condition is likely to result from obstructed crankshaft oil passages?

Obstructed crankshaft oil passages can lead to a lack of adequate lubrication to critical components, particularly the rod bearings. These bearings rely on a consistent supply of oil to maintain a protective film that prevents metal-to-metal contact. When oil passages are blocked, the flow of oil to these bearings is reduced or cut off completely, resulting in increased friction and heat in the area. This excessive wear can lead to damaged or failed rod bearings over time.

The other outcomes listed, such as increased oil pressure, greater fuel efficiency, or decreased engine temperature, are unlikely in the presence of obstructed oil passages. Instead of an increase in oil pressure, one would typically expect the oil pressure to drop due to insufficient oil flow. Additionally, the lack of proper lubrication would typically lead to decreased efficiency and increased operating temperatures, rather than improvements in these areas. Thus, the condition of worn rod bearings is the most directly attributed consequence of obstructed crankshaft oil passages.