I think you are looking at the break in period for gas engines. If you look at the Diesel supplement:
The diesel engine does not require a break-in period due to its construction. Normal operation is allowed, providing the following recommendations are followed:
• Warm up the engine before placing it under load.
• Do not operate the engine at idle for prolonged periods.
• Use the appropriate transmission gear to prevent engine lugging.
• Observe vehicle oil pressure and temperature indicators.
• Check the coolant and oil levels frequently.
• Vary throttle position at highway speeds when carrying or towing significant weight.