2003-2004 Dodge 5.9L Cummins Engine Oil

Engine oil on the 2003-2004 Ram 5.9L Cummins

The common-rail 5.9L holds 12 US quarts with the filter, which works out to three one-gallon jugs. The factory interval is 15,000 miles or 12 months under normal service and 7,500 miles or six months under severe service. The oil also has a job many owners forget: the 2003-2004 turbo is oil-fed and oil-drained with no water-cooled center section, so give it 30 seconds to three minutes of idle after towing to keep oil from coking in the bearing housing. More for this engine is on the Cummins hub.

Picking a grade and an interval

If the truck never sees temperatures below 0F, 15W-40 is the factory grade. 5W-40 full synthetic covers every temperature, which makes it the pick for a truck that heads north in winter. On modified common-rail trucks, Turbo Diesel Register writers favored CI-4+ rated oil and 4,000 to 4,500-mile changes. Most of the diesel oils here carry the CK-4 category on the label, and the Lucas Magnum High TBN 15W-40 is labeled CI-4. Additives such as TBN boosters, stabilizers and friction reducers are an addition to fresh oil of the right grade, not a replacement for a change.

What we carry

• Hot Shot's Secret: Green Diamond 15W-40 in semi-synthetic and full synthetic, Green Diamond 5W-40, Blue Diamond 5W-40, Black Diamond Outlaw 15W-40 and 10W-30, ADRENALINE R-Series racing oils, plus TBN Booster, FR3 Friction Reducer and The Original Stiction Eliminator.
• Lucas Oil: 15W-40 CK-4, Synthetic 15W-40 CK-4, Magnum High TBN 15W-40 CI-4, Synthetic Blend 10W-30 CK-4, Heavy Duty and Synthetic Heavy Duty Oil Stabilizer, and TB Zinc Plus break-in additive for a freshly built engine.
• XDP: X-Factor oil additive.

Fitment notes

Oil is not truck-specific, so this grid also shows grades cataloged for other engines, such as Green Diamond 0W-20 light-duty diesel oil, 10W-30 blends and the 5W-20 and 20W-50 racing oils. For a 2003-2004 5.9L, the factory schedule lists 15W-40 and 5W-40 only, so read the label before you pick anything else. Grab a filter with the oil.

Frequently asked questions

What oil weight does a 2003-2004 Ram 5.9L Cummins take?

The factory schedule lists 15W-40 when temperatures stay above 0F and 5W-40 full synthetic for all temperatures. Hot Shot's Secret and Lucas Oil both offer 15W-40 here, and Hot Shot's Secret offers 5W-40 in Green Diamond and Blue Diamond.

How many gallons do I need for an oil change?

Three. The engine holds 12 US quarts with the filter, so three one-gallon jugs fill it. Pick up the filter at the same time.

How often should I change oil on a tuned or towing 5.9L?

The factory severe-service interval is 7,500 miles or six months. Turbo Diesel Register writers favored 4,000 to 4,500-mile changes on modified common-rail trucks. Shorter intervals also help the turbo, whose bearing housing has no coolant jacket and depends on clean oil.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.