A. First, make sure you know your engine manufacturer recommendations and guidelines.

Second, most heavy-duty engine oil suppliers have multiple performance levels available. Considering the investment cost of a diesel engine, downtime and overall maintenance costs, it is highly recommended to investigate what products are available to optimize engine oil performance and engine protection under extended oil change intervals. 

Third, implement and carry out a quality oil analysis program, partnering with an oil analysis laboratory or your engine oil provider. Failure to go about extended engine oil change intervals correctly can only result in problems down the road. It is recommended to use or at least inquire about premium or higher performance engine oils, used in combination with a quality oil analysis program.