Roller lifter wear, sticking, or looseness can be caused by high carbon content in the engine oil, which is the product of combustion and can be caused by a malfunctioning EGR and/or EPR system.
When you encounter this type of condition, be sure the EGR and EPR systems are functioning properly and that there are no exhaust leaks in the air inlet system. If the above systems are found to be OK, the operator of the vehicle involved should be questioned about driving conditions and driving habits. Extended idle periods and/or low speed operation will necessitate more frequent oil changes. Refer to the appropriate Owner’s Manual for recommended oil change intervals for severe service driving conditions.