2026 Ram 2500 Maintenance Schedule: Cummins Diesel & 6.4L HEMI Service Guide

The 2026 Ram 2500 is engineered for demanding work — whether you’re hauling heavy loads near Fontana, navigating construction routes around San Bernardino, or towing through Rancho Cucamonga. Keeping this heavy-duty truck performing at its best requires understanding the specific maintenance needs of its two available powertrains: the 6.7L Cummins Turbo Diesel and the 6.4L HEMI V8. Proper upkeep safeguards engine health, optimizes fuel efficiency, and preserves the vehicle’s long-term value.

Cummins 6.7L Turbo Diesel Maintenance

The 6.7L Cummins Turbo Diesel in the Ram 2500 is built with robust components designed to endure high torque and extended heavy-duty use. However, diesel engines require specialized maintenance practices compared to gasoline counterparts.

Oil changes are the foundation of Cummins diesel care. Mopar recommends an oil change interval not to exceed 15,000 miles or 12 months, whichever comes first. This interval can be significantly shorter depending on your truck’s workload — frequent towing, extended idling, or driving in dusty environments common around Fontana and Rancho Cucamonga may call for service closer to every 7,500 miles. The Ram 2500’s oil life monitoring system uses sensor data to analyze engine hours and driving conditions, providing a tailored alert when service is due.

Fuel filter replacement is another critical diesel maintenance item. The Cummins uses a dual-stage fuel filtration system with both an engine-mounted and a frame-mounted filter. These should be replaced every 15,000 miles or 12 months under normal conditions — more frequently if you tow regularly or operate in dusty environments. Clean fuel delivery is essential to protect the injectors and high-pressure fuel pump from damage.

Diesel Exhaust Fluid (DEF)

The 2026 Ram 2500 Cummins diesel uses a Selective Catalytic Reduction (SCR) system that requires Diesel Exhaust Fluid (DEF) to reduce nitrogen oxide emissions. DEF is a solution of urea and deionized water that is injected into the exhaust stream, converting harmful NOx gases into nitrogen and water vapor. Maintaining proper DEF levels is not optional — if the DEF tank runs low, the truck will display progressive warnings, reduce engine power, and can eventually prevent the engine from starting until the tank is refilled.

Cummins recommends topping off the DEF tank at each fuel refill to avoid running low. The Ram 2500’s instrument cluster includes a DEF level gauge and a warning system that alerts you well before the tank is empty. Always use API-certified DEF fluid that meets ISO 22241 specifications — never dilute it or substitute other fluids. DEF is available at most fuel stations and auto parts stores.

Emissions System and Crankcase Ventilation

The diesel particulate filter (DPF) traps soot and particulate matter from exhaust gases, periodically burning them off through an automatic regeneration process. If you see a regeneration notification while driving, keep the engine running until the cycle completes. Regular highway driving helps the DPF regenerate fully — short trips and city driving alone are not sufficient to keep the emissions system healthy.

The Cummins engine also uses a Closed Crankcase Ventilation (CCV) system with a replaceable filter mounted on top of the valve cover. This filter captures oil vapors and blow-by gases before they can re-enter the intake system, protecting the turbocharger compressor wheel from oil buildup that degrades efficiency over time. The factory-recommended replacement interval for the CCV filter is approximately 67,500 miles, though the Ram 2500’s overhead console will display an alert if the filter becomes clogged before that point. Neglecting this filter can lead to increased oil consumption, turbo contamination, and diagnostic trouble codes.

6.4L HEMI V8 Maintenance

The 6.4L HEMI V8 gasoline engine offers a different maintenance profile. Oil changes should not exceed 8,000 miles, 12 months, or 350 engine hours — whichever comes first. Using high-quality synthetic oil that meets Mopar’s specifications helps protect the engine under demanding conditions such as towing or stop-and-go driving.

Spark plug replacement is another key maintenance item for the 6.4L HEMI. The HEMI’s dual-plug design means 16 spark plugs total — two per cylinder. Per the manufacturer’s recommended schedule, the factory iridium spark plugs should be replaced at approximately 100,000 miles. Delaying spark plug service beyond the recommended interval can lead to misfires, reduced fuel economy, and increased emissions.

Routine air filter changes help prevent dust and debris buildup, which is particularly important for trucks operating in the dusty environments common around Fontana and San Bernardino. Ensuring the cooling system is functioning properly also protects the engine from overheating during heavy loads or hot weather.

Oil Change Intervals at a Glance

Key Routine Inspections and Service Intervals

Regardless of engine choice, the Ram 2500’s heavy-duty components require consistent attention to maintain reliability and performance.

Brake inspections should be performed at every service visit, with increased frequency for trucks regularly towing trailers or hauling heavy payloads. The Ram 2500’s larger brake components should be examined for pad thickness, rotor condition, and hydraulic system integrity. Early detection of wear helps avoid costly repairs and ensures safe operation on busy roads around Fontana and Riverside.

Tire rotation every 6,000 to 8,000 miles promotes even wear and supports balanced handling and traction. Due to the Ram 2500’s substantial weight and frequent load-bearing tasks, uneven tire wear can develop quickly if neglected. Suspension and steering components also benefit from periodic inspections to identify worn bushings, ball joints, or tie rods that could affect ride comfort and control.

Transmission fluid and filter changes are recommended every 60,000 miles under normal conditions, or every 30,000 miles for trucks used in heavy towing or severe-duty applications. Coolant should be flushed and replaced at 10 years or 150,000 miles, whichever comes first. Brake fluid, differential oil, and transfer case fluid (on 4WD models) also require periodic checks and changes to maintain system durability under load.

Air filters — both engine and cabin — should be evaluated regularly. In dusty environments common near Fontana’s industrial areas, clogged filters can reduce engine efficiency and cabin air quality. Replacing these filters according to manufacturer guidance helps maintain optimal airflow and protects engine components from contaminants.

Schedule Your Ram 2500 Maintenance in Fontana

Keeping your 2026 Ram 2500 running at peak performance requires expert technicians who understand the unique demands of heavy-duty trucks. At Fontana Chrysler Dodge Jeep Ram, our service team provides comprehensive maintenance tailored to both the Cummins diesel and the 6.4L HEMI — using genuine Mopar parts designed specifically for your Ram.

Whether you’re comparing diesel engine options for your next heavy-duty truck or maintaining your current Ram 2500, our team can help. Learn more about how the Cummins stacks up against the competition in our Cummins vs. Duramax vs. Powerstroke comparison guide.