5.9 Cummins Engine Oil Guide

Applicable Models:

1989 - 2007 Dodge Ram 2500, Ram 3500, Ram 4500, Ram 5500

Applicable Engine(s):

5.9L Cummins 6BT (12v), 5.9L Cummins ISB (24v)

Engine Oil Capacity:

12.0 U.S. quarts with filter change

Engine Oil Viscosity Spec:

Refer to chart below for full breakdown

Motor oil is the lifeblood of your engine, providing lubrication and cooling to a complex system of fast moving mechanical parts under significant load. Routine oil changes ensure that old, broken down engine oil is replaced before it loses its chemical and mechanical properties, thus maximizing protection against wear. Service intervals vary between 12v, 24v, and 24v common rail Cummins engines (see schedule below). Always follow the manufacturers suggested oil change interval and adhere to the alternative "severe duty" schedule if you meet 1 or more of the requirements.

5.9 Cummins Oil Change Information

All 5.9L Cummins turbodiesels (6BT and ISB) feature a 12 quart oil capacity (with filter change) and share the same oil filter. Engine oil should be replaced per the oil change interval chart below using the appropriate viscosity listed in the applicable chart below. Overfilling or underfilling the crankcase may result in oil aeration and compromised oil pressure. Always verify oil level on dipstick after running engine and allowing to cool for 15 minutes (oil in the top of the engine must drain back into the crankcase before checking oil fill level). Neither Cummins nor Chrysler recommend the use of a supplemental oil additive in 5.9L diesel engines. A high quality, synthetic engine oil is recommended for all engines. Always fill the oil filter with roughly 1 quart of clean engine oil before installing, which will help prevent dry starts and ensure oil pressure builds quickly after changing the oil.

5.9 Cummins Oil Change Intervals

Severe service conditions include towing, hauling, driving in stop-and-go traffic, taking frequent short trips, operating in hot weather, operating in extremely cold weather, and frequent periods of excessive idling; always following the service interval that applies to your operating conditions. Most vehicles will fall under the severe service category, unless your truck is used for the sole purpose of commuting and your route sees limited city driving.

Model Years Normal Service Interval Severe Service Interval
1989 - 1998 (6BT, 5.9L Cummins 12v) 6,000 miles/6 months 3,000 miles/3 months
1998.5 - 2002 (ISB, 5.9L Cummins 24v) 7,500 miles/6 months 3,750 miles
2003 - 2007 (ISB, 5.9L Cummins 24v) 15,000 miles/6 months 7,500 miles/6 months

5.9 Cummins Oil Change Parts List

Fleetguard is Cummins' service parts brand and is the recommended replacement oil filter for all Cummins turbodiesels; avoid cheap aftermarket filters. Replace the engine oil pan drain plug when the edges of the head begin to show signs of wear or the gasket develops a leak. Replace the oil fill cap when it begins to show signs of degradation to prevent particles/pieces from dislodging and falling into the crankcase.

Description Part Number
Engine oil filter Fleetguard FL16035 (all 5.9L Cummins)
Oil pan drain plug 1989 - 1993 MOPAR 4293859
1994 - 2002 MOPAR 4778578
2003 - 2007 MOPAR 05080631AB
Engine oil fill cap 1989 - 1998 Cummins 4962608
1998.5 - 2007 Cummins 3973511

1989 - 1998 5.9 Cummins 6BT Engine Oil Viscosity Chart (12 valve)

Ambient Temperature Range Oil Viscosity
Greater than 10° F SAE 15W-40
0 - 30° F (w/ out using engine block heater) SAE 10W-30
Less than 0° F (must use engine block heater) SAE 10W-30
Less than 0° F (w/ out using engine block heater) SAE 5W-30

1998.5 - 2002 5.9 Cummins ISB Engine Oil Viscosity Chart (24 valve)

Ambient Temperature Range Oil Viscosity
Greater than 10° F SAE 15W-40
0 to 30° F (w/ out using engine block heater) SAE 10W-30
-10° F to 30° F (must use engine block heater) SAE 10W-30
-10 to 0° F (must use engine block heater) SAE 5W-30

2003 - 2007 5.9 Cummins ISB Oil Viscosity Chart (24 valve, common rail)

Ambient Temperature Range Oil Viscosity
Greater than 0° F SAE 15W-40
All temperatures SAE 5W-40 full synthetic

5.9 Cummins Engine Oil Recommendations

Diesel Hub recommends the following Amsoil products for Dodge Ram models equipped with the 5.9L Cummins turbodiesel:

Amsoil synthetic engine oils offer:

• Superior protection against fuel dilution and oil consumption

• Superior resilience against thermal, mechanical, and chemical breakdown of engine oil

• Improved oil flow and engine protection in sub-zero temperatures and during cold starts

Amsoil is a leading manufacturer of synthetic oils and lubricants, including a line of engine oils engineered to meet the stringent demands specific to diesel engines.

Synthetic engine oil is superior in every way, shape, and form than conventional petroleum based engine oils. Synthetic motor oil features a significantly higher resistance to thermal breakdown, chemical breakdown (contamination from fuel dilution and exhaust soot), and mechanical breakdown (shear). It is backwards compatible with ALL engines regardless of age and type.

5.9 Cummins Engine Oil Change Procedures

Note: 1994-1998 model year Cummins 6BT featured in procedures below

Click any thumbnail to view fullsize, detailed image

Cummins oil pan drain bolt

• Park the vehicle, set the parking brake, and allow the engine to cool for ~ 1 hour before changing the motor oil.

• Place a suitable drain pan (minimum 12 quart capacity) below the engine oil pan drain plug.

• Remove the drain plug and allow the oil to drain. When the engine oil has drained completely, reinstall the drain plug. Install drain plug snug; do not overtighten. If the drain plug seal is compromised it should be replaced.

5.9L Cummins oil filter location

• Reposition the drain pan below the oil filter, then remove the oil filter (passenger side of engine block behind thermostat housing).

Filling new oil filter with clean motor oil

• Fill the replacement oil filter with ~1 quart of fluid (slightly less than a quart is desirable as it will reduce the chances of spilling during installation).

• Lubricate the oil filter o-ring gasket with a liberal amount of clean engine oil.

Installing Fleetguard oil filter

• Reinstall the oil filter; tighten by hand only. There is no need to overtighten the oil filter, simply snug it up as tight as possible by hand.

Filling crankcase with new engine oil

• Add the remaining engine oil (12 quarts minus what was poured into the oil filter) to the crankcase through the engine fill tube located at the front of the timing cover.

• Verify the engine oil level using the engine oil dipstick.

• Start the engine and check for leaks at the oil filter and oil pan drain plug.

• Recheck engine oil level after allowing the engine to cool.