Use of exhaust gas recirculation (EGR) with heavy-duty diesel engines has been hampered in the past by increased particulate, increased oil degradation, loss of power, etc. This study was focused on assessing the effect of EGR on the oil degradation and intake system fouling on a modern, low-emitting diesel engine. A series of 300-hour tests were run using an accelerated test condition. Based upon this work it was concluded that chemical and physical properties of the lubricating oil were not degraded with use of EGR. However, depending upon the design of the EGR system, the subsequent contamination of the turbocharger and the air-to-air charge cooler can be unacceptable. This work shows that with modern engines, low-sulfur fuels, and proper design, EGR can now be considered an acceptable part of a manufacturer's emissions reduction strategy.