1998.5-2002 Dodge 5.9L Cummins Engine Oil

Oil grade and capacity for the 1998.5-2002 5.9L Cummins

The 24-valve Cummins is a cast-iron inline-six with a solid-lifter cam and four valves per cylinder. The factory viscosity chart goes by outside temperature: SAE 15W-40 above 10 F, 10W-30 from 0 to 30 F if the truck has no block heater, and 5W-30 from -10 to 30 F with a block heater. Capacity is 12 quarts with the filter, which is three one-gallon jugs. Change it every 7,500 miles or 6 months, or every 3,750 miles if you tow.

Keep an eye on the dipstick

Low oil between changes on a 24-valve is not always oil being burned. The crankcase breather on 1998.5-2002 trucks sits at the front of the engine and can push a lot of oil out on steep descents. It also drips on the driveway and gets mistaken for a front-axle seal leak. Dodge TSB 09-002-02 moves the breather inlet back alongside the engine, where it is less affected by oil level on grades. The other common drip is the vacuum pump shaft seal, where the power steering pump shaft enters the rear of the tandem vacuum and power steering pump. That seal leaks engine oil as the truck ages.

Conventional, synthetic blend or full synthetic

Viscosity comes first and base stock is your call. For 15W-40, this collection has Lucas Oil 15W-40 CK-4, Lucas Synthetic 15W-40 CK-4 and Lucas Magnum 15W-40 High TBN CI-4, plus Hot Shot's Secret Green Diamond 15W-40 in semi-synthetic and full synthetic and Black Diamond Outlaw 15W-40 full synthetic. For cooler weather there is Lucas Synthetic Blend 10W-30 CK-4, Hot Shot's Green Diamond 10W-30 and Black Diamond Outlaw 10W-30. The collection also lists grades that are not on this engine's chart, such as Green Diamond 0W-20 Light Duty Diesel oil, 5W-40 oils, and ADRENALINE R-Series racing oils in 5W-20 and 20W-50. For a 24-valve that drives and tows, stay with the chart, and call us before you run anything off it.

Oil stabilizers and additives

If you run an additive, the choices here are Lucas Heavy Duty Oil Stabilizer and Synthetic Heavy Duty Oil Stabilizer, Lucas TB Zinc Plus, which is labeled as an engine break-in additive, Hot Shot's Secret TBN Booster fortified oil stabilizer, FR3 Friction Reducer and The Original Stiction Eliminator, and the XDP X-Factor high performance oil additive. Read each product page for what it is made to do and how much to add. The factory oil change interval stays the same either way.

What we carry

Engine oil and oil additives from Hot Shot's Secret and Lucas Oil, plus an oil additive from XDP. Most of the engine oil comes in one-gallon jugs, so plan on three per change. Filters are in the Filters section of this Oil System menu.

Fitment notes

Oil does not care about cab, bed or drivetrain. The variables are outside temperature and duty. The 12-quart capacity and the grade chart above apply to the 1998.5-2002 5.9L Cummins in the Ram 2500 and 3500. If you are not sure whether your truck has the 24-valve or the earlier 12-valve it replaced in mid-1998, verify by VIN or call the shop.

Frequently asked questions

What oil does a 1998.5-2002 Ram 2500 with the 5.9L Cummins take?

SAE 15W-40 above 10 F, which is most of the year in Florida. The chart allows 10W-30 from 0 to 30 F without a block heater and 5W-30 from -10 to 30 F with one. Fill with 12 quarts including the filter.

How many gallons of oil does a 24-valve Cummins oil change take?

Three. Capacity is 12 quarts with the filter, so three one-gallon jugs cover a full change. Do it every 7,500 miles or 6 months, or every 3,750 miles if you tow.

My 24-valve loses oil between changes. Is it burning it?

Not necessarily. The front-mounted crankcase breather can push oil out on steep descents and drips by design, and the vacuum pump shaft seal leaks engine oil as it ages. Check for drips under the front of the engine and around the vacuum pump before you assume consumption.

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.