When EGR systems are added to diesel engines, what oil properties must change?

The correct choice highlights that when Exhaust Gas Recirculation (EGR) systems are introduced to diesel engines, it is essential for the engine oil to adapt in order to handle the additional byproducts generated through this emissions control technology. EGR systems work by recirculating a portion of the exhaust gases back into the engine's intake. This process reduces nitrogen oxides (NOx) emissions but also leads to an increase in soot production within the oil.

To manage the increased soot levels, the oil must have enhanced properties that allow it to suspend and disperse the soot particles effectively, preventing them from causing damage to engine components. Additionally, a more alkaline oil is necessary to counterbalance the increased acidity that can occur due to the combustion of recirculated exhaust gases. Alkalinity in oil helps neutralize acids formed as a byproduct of combustion, thus ensuring better engine protection and longevity.

In summary, the adaptation of the oil to handle more soot and become more alkaline is crucial for maintaining engine performance and extending its life in the context of an EGR-equipped diesel engine.