There's no single answer. However, here's a general guideline:
* Older Cummins engines (pre-2007): These often had recommended oil change intervals of 7,500 to 15,000 miles for conventional oil, potentially longer with synthetic. However, 10,000 miles is frequently cited as a reasonable compromise even with synthetics for these engines.
* Newer Cummins engines (2007 and later): These engines often have more sophisticated oil monitoring systems and may recommend longer intervals, sometimes up to 15,000 miles or even more with certain types of synthetic oils *if the monitoring system indicates it's appropriate*. However, many owners and mechanics still prefer shorter intervals for optimal engine life, especially under heavy use. Using the in-vehicle monitor is key, but consider 10,000-15,000 miles as a *possible* range only if the monitor allows it.
* Severe Service: Towing heavy loads, frequent idling, dusty environments, or extreme temperatures all constitute "severe service." In these cases, you should significantly shorten your oil change interval, regardless of the recommended mileage. 5,000-7,500 miles is a common suggestion for severe service.
Crucially: Always consult your owner's manual for the specific recommendations for your year and model of Dodge Cummins. The manual will provide the most accurate information based on your engine's specifications and intended use. Ignoring this advice could lead to engine damage.
Don't just rely on mileage. Pay attention to the oil's condition. If it's dark, dirty, or smells unusual, it's time for a change regardless of mileage. Consider using an oil analysis service periodically to get a more precise understanding of your engine's oil health.
