According to best practices, how should a diesel engine be broken in?

Varying engine speed and load during the break-in period of a diesel engine is crucial for ensuring proper seating of engine components such as piston rings and bearings. This practice helps create a more uniform wear pattern, which can enhance the overall performance and longevity of the engine.

When an engine operates under a range of speeds and loads, it allows various components to experience different operating conditions, which helps them adapt and form a better fit over time. This variability prevents the components from becoming too comfortable at a single speed and load setting, which could lead to uneven wear and potential issues later in the engine's life.

In contrast, maintaining a constant speed or using high RPMs can lead to improper seating, potentially resulting in reduced efficiency and increased oil consumption. Performing regular oil changes is certainly important for engine maintenance, but it is not sufficient as a sole measure during the break-in process. Proper break-in techniques are essential for setting up the engine for optimal performance in the long term.