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Cummins/Onan RDJC Engine

Name: Cummins/Onan RDJC Engine
Brand: Cummins/Onan

The Cummins/Onan RDJC is a 120 L 4-cylinder engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the 12.5RDJC-518R, 12.5RDJC-53CR, 12.5RDJC-57R and 15.0RDJC-18R. It holds 6 L (1.6 gal) of oil and 12 L (3.2 gal) of coolant.

Also known as: Onan RDJC

Part of the Cummins/Onan RDJC engine family — 2 variants share parts & fitment.

120.0 L

Displacement

Cylinders

1800 rpm

Rated speed

6.0 L

Oil capacity

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Procedures Wiring

Engine specifications

Oil capacity	6.0 L
Coolant capacity	12.0 L
Displacement	120.0 L
Cylinders	4
Rated speed	1800 rpm

Generator sets powered by this engine

Cummins/Onan 12.5RDJC-518RCummins/Onan 12.5RDJC-53CRCummins/Onan 12.5RDJC-57RCummins/Onan 15.0RDJC-18RCummins/Onan 15.0RDJC-3CRCummins/Onan 15.0RDJC-4RCummins/Onan 15.0RDJC-4XRCummins/Onan 15.0RDJC-5DRCummins/Onan 15.0RDJC-9XR

How to read your Cummins/Onan engine serial & model number →

Troubleshooting

Symptoms & remedies

Symptom	Cause	Remedy
Engine does not crank.	Battery dead, loose connections, incorrect wiring, or faulty starter motor.	Check 12 VDC to ground at battery BT1 and at starter motor Bl. Check B+ present at TB11, K13, S1, and M11. Check battery cables for polarity and tightness at battery and starter motor. If battery is dead, check if centrifugal switch S1 is open to ground. Replace S4 or charge battery. Jumper battery cable connection to ground at starter. Check starter motor. With S11 at START, jumper K11 contacts to starter solenoid. Start relay K11 is defective; replace it.
Engine cranks but does not start.	Faulty switch or lead connections.	Check 12 VDC present between start terminal on S11 and ground (TB11-1) with S11 at START. Check 12 VDC present between M11-B+ and ground TB11-1 with S11 at START. Replace faulty switch S11 if necessary. Check lead from TB12-4 to fuel pump; check fuel pump and replace if necessary.
Engine starts but stops when start switch is released.	Faulty switch or lead connections.	Connect voltmeter from 12 VDC to ground at battery BT1 and at starter motor Bl. Check B+ present at TB11, K13, S1, and M11. Check battery cables for polarity and tightness at battery and starter motor. If battery is dead, check if centrifugal switch S1 is open to ground. Replace S4 or charge battery. Jumper battery cable connection to ground at starter. Check starter motor. With S11 at START, jumper K11 contacts to starter solenoid. Start relay K11 is defective; replace it.
No build up of AC output voltage.		Is Field Breaker CB21 on control panel ON? If not, step 2. Connect jumper wire across terminals of Field Breaker, CB21. Does AC output voltage build up? If yes, replace Field Breaker. If no, push to reset Field Breaker. Does AC output voltage build up? If yes but is high, low, unstable, or causes tripping of Field Breaker, refer to Tables B, C, or D. If no, step 4. Disconnect alternator stator leads 1 & 2 from TB21-1 and TB21-2 on VR22. Is reference voltage across 1 & 2 20 VAC or more? If not, refer to step 14.
AC output voltage builds up, but is unstable.		Are there any loose or broken wires or connections on voltage regulator assembly VR22? If yes, step 3. Is W9 (exciter field) wiring harness from VR22 to End bell OK? If no, replace PC Board VR21. Do not replace the printed circuit board until the trouble not on the PC board has been located and corrected to avoid damage to new PC board.
AC output voltage builds up, but is high or low.		Is set running at correct RPM? (See appropriate engine manual to set RPM) If no, step 3. Does adjustment of Voltage Adjusting knob for R22 on VR22 result in correct output voltage? If no, step 4. Does adjustment of potentiometer R26 on VR21 result in correct output voltage? If no, refer to step 5. Is correct voltage reference V4 to V1, V2, or V3 on VR21 being used? Refer to Figure 6. If no, replace voltage regulator PC board VR21. Do not replace the printed circuit board until the trouble not on the PC board has been located and corrected to avoid damage to new PC board.
AC output voltage builds up, but Field Breaker trips.		Does AC output voltage build up to 140% or more of rated voltage before Field Breaker trips? If yes, are there any loose or broken wires or connections on VR22? If no, is diode CR15 on VR21 OK? If no, are T21 windings and connections OK? If no, are generator stator leads properly connected? Refer to Figure 6. Replace VR21 if necessary. Are diodes CR1, CR2, CR3, CR4, CR5, CR6 in rotating rectifier assemblies OK? Check all diodes - more than one may be defective. Is brushless exciter stator winding OK? Is generator rotor field winding OK? If no, is brushless exciter rotor windings OK?

Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Dry type		140-0636	50 hr	Amazon eBay
Fuel filter			122-0325	600 hr	Amazon eBay $75.00
Oil filter	Full Flow Type		122-0185	200 hr	Amazon $8.99 Amazon eBay $19.55 eBay
Battery	SAE group 1H, 2 in series, amp/hr SAE 20-hr (nominal) 105		—
Belt	Deflection 1/2-inch with about 15 pounds force midway between fan pulley and belt tightener pulley		511-0066		Amazon eBay
Coolant	Clean, soft (alkali free) water with rust and scale inhibitor	12.0 quarts	—
Coolant filter			130-0626		Amazon eBay
Oil	API CD/SD or CD/SE	6.0 U.S. quarts	—	100 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Repair guides

Step-by-step procedures compiled from the Cummins/Onan service manual for this engine.

Service intervals

Item	Action	Hours	Notes
Fuel supply	Check	8 hr	See Note 1
Generator set	Inspect	8 hr
Oil level	Check	8 hr	See Figure 17
Air cleaner	Check	50 hr	More often in dusty conditions
Crankcase oil	Drain	50 hr	First service — Drain and replace after first 50 hours of operation; drain while engine is still hot
Crankcase oil	Change	100 hr
Fuel condensation traps in lines and filters	Drain	100 hr
Governor linkage	Clean	100 hr	See Figure 17
Battery condition	Check	200 hr
Crankcase breather	Clean	200 hr	See Figure 17
Oil filter	Replace	200 hr
Generator slip rings and brushes (prior to Spec AA)	Check	500 hr	Replace if worn to 5/16"
Start-disconnect circuit	Check	500 hr	Call Onan serviceman
Valve clearances	Check	500 hr
Primary filter	Change	600 hr	Figure 18
Baffle in pulsation filter	Replace	2000 hr	Figure 17
Holes in rocker box oil line	Clean	2000 hr
Valves	Other	2000 hr	Grind valves (if required)
Secondary fuel filter	Change	3000 hr
General overhaul	Other	5000 hr	If required - Call Onan serviceman (Note 3)

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Cam Tappet Diameter	.8725 (min) - .8730 (max)	inch
Clearance	Cam Tappet Hole Diameter	.8755 (min) - .8765 (max)	inch
Clearance	Camshaft Bearing Clearance Limit	.0015 (min) - .0030 (max)	inch
Clearance	Camshaft Bearing Journal Diameter, Front	2.500 (min) - 2.505 (max)	inch	room temperature 70 degrees F
Clearance	Camshaft Bearing Journal Diameter, Rear	1.1875 (min) - 1.1880 (max)	inch	room temperature 70 degrees F
Clearance	Camshaft End Play	.007 (min) - .039 (max)	inch
Clearance	Connecting Rod Bushing (piston pin clearance)	.0002 (min) - .0007 (max)	inch	Thumb Push Fit
Clearance	Connecting Rod Clearance, Bearing-to-Crankshaft	.001 (min) - .003 (max)	inch
Clearance	Connecting Rod Large Bore Diameter	2.1871 (min) - 2.1876 (max)	inch
Clearance	Connecting Rod Small Bore Diameter	1.044 (min) - 1.045 (max)	inch
Clearance	Crankshaft Connecting Rod Journal Diameter	2.0600 (min) - 2.0605 (max)	inch
Clearance	Crankshaft End Play	.010 (min) - .015 (max)	inch
Clearance	Crankshaft Main Bearing Clearance	.0030 (min) - .0043 (max)	inch
Clearance	Crankshaft Main Bearing Journal Diameter	2.2437 (min) - 2.4445 (max)	inch
Clearance	Crankshaft Rod Bearing Clearance	.0019 (min) - .0038 (max)	inch
Clearance	Cylinder Block Bore Diameter (valve guide)	.467 (min) - .468 (max)	inch
Clearance	Cylinder Diameter Limits	3.4995 (min) - 3.5005 (max)	inch
Clearance	Distance Center Large Bearing Bore to Small Bore	5.998 (min) - 6.002 (max)	inch
Clearance	Exhaust Valve Guide Clearance	.0025 (min) - .0045 (max)	inch
Clearance	Exhaust Valve Stem Diameter	.3405 (min) - .3415 (max)	inch
Clearance	Intake Valve Guide Clearance	.0015 (min) - .0025 (max)	inch
Clearance	Intake Valve Stem Diameter	.3405 (min) - .3415 (max)	inch
Clearance	Piston Clearance to Cylinder Wall (measured 90 degrees to pin, just below oil ring groove)	.0055 (min) - .0075 (max)	inch
Clearance	Piston Ring Width, 2nd	.0925 (min) - .0935 (max)	inch
Clearance	Piston Ring Width, 3rd	.0925 (min) - .0935 (max)	inch
Clearance	Piston Ring Width, Top	.0925 (min) - .0935 (max)	inch
Clearance	Valve Guide Inside Diameter, Exhaust (after reaming)	.344 (min) - .345 (max)	inch
Clearance	Valve Guide Inside Diameter, Intake (after reaming)	.342 (min) - .343 (max)	inch
Clearance	Valve Guide Outside Diameter	.4690 (min) - .4695 (max)	inch
Clearance	Valve Seat Bore Diameter	1.361 (min) - 1.362 (max)	inch
Clearance	Valve Seat Depth (from cylinder head face)	.433 (min) - .439 (max)	inch
Clearance	Valve Seat Insert Outside Diameter	1.364 (min) - 1.365 (max)	inch
Gap	Centrifugal start-disconnect switch point gap	.020	inch
Gap	Piston Ring Gap	.010 (min) - .020 (max)	inch
Other	AC frequency regulation	5	%
Other	Cranking time limit (cranking limiter)	45 to 90	seconds	depending on ambient temperature
Other	Engine fails to start - cranking stopped by cranking limiter	45 to 120	seconds
Other	Engine speed equals frequency x 30 on 4 pole generator	1800	rpm	60 hertz
Other	Exhaust Valve Face	45	degrees
Other	Governor preheat and crank time	about 20	seconds	RUN position
Other	Intake Valve Face	42	degrees
Other	Valve Guide Length	1-25/32	inch
Other	Valve Seat Angle	45	degrees
Other	Valve Seat Available Oversizes	.002, .005, .010, .025	inch
Other	Valve Seat Width	3/64 (min) - 1/16 (max)	inch
Pressure	Oil pressure gauge minimum after start	at least 20	psi
Pressure	Valve Spring Load, Valve Closed	45 (min) - 49 (max)	lbs.
Pressure	Valve Spring Load, Valve Open	87.2 (min) - 97.2 (max)	lbs.
Speed	Centrifugal switch closes	about 900	rpm	during speed buildup
Speed	Governed speed variation, no-load to full-load	does not vary more than 3 hertz	hertz	no load to full load
Torque	Cylinder Head Bolt Torque	44-46	lbs.-ft
Torque	Generator (end bell)	35-38	ft. lbs.
Torque	Glow Plug Torque	10-15	lbs.-ft
Torque	Rotating rectifier diodes	25 (or finger tight plus a quarter turn)	in. lb.
Torque	Rotor through stud	130 to 150	ft. lbs.
Torque	Stator through stud	55-60	ft. lbs.
Valve clearance	Valve Clearance, Exhaust	.016	inch	cold
Valve clearance	Valve Clearance, Intake	.011	inch	cold
Voltage	AC voltage regulation	Plus or Minus 3	%

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Capacity	Notes
Coolant	Clean, soft (alkali free) water such as rain water; standard anti-freeze solution if exposed to freezing	Add an approved rust and scale inhibitor; anti-freeze proportioned to protect to at least 10 F below the lowest expected temperature	12.0 quarts	Water capacity (radiator cooled) 12 quarts; check radiator drain valve closed and cylinder block drain plug tight.
Engine oil	Above 30 F: SAE 30; 0 F to 30 F: SAE 10W or 5W-30; Below 0 F: SAE 5W-30	API designation CD/SD or CD/SE. Use CC oil for the first fill only (50 hours)	6.0 U.S. quarts	Multigrade oils recommended at 30 F and below, not recommended above 30 F. Add oil of same brand between changes.
Fuel	Number 2 diesel fuel (Number 1 diesel can be used below 32 F, during long periods of light load, or if preferred)	Low sulfur content fuel having a pour point at least 10 F below the lowest expected temperature		Keep fuel clean and protected from adverse weather; leave room for expansion when filling the tank.
Grease	Non-conductive grease			Light coating on battery terminals retards corrosion.
Other	Approved rust inhibitor			Add to coolant in closed cooling systems.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Centrifugal switch adjustment adjustment

Tools: Feeler gauge

Locate switch on the gear cover on the side of the engine above the oil filter.
Loosen the stationary contact.
Adjust the point gap to .020 inch.
Replace burned or faulty points.

Charge rate adjustment adjustment

⚠ Adjust only when plant is stopped.

Adjust only when plant is stopped.
Move the adjustable resistor slide tap until the charging rate is approximately 2 amperes.
For frequent starts, move slide tap nearer the ungrounded lead to increase charging rate slightly.
Avoid overcharging.

Fan belt adjustment adjustment

Loosen the nut on the belt tightener pulley shaft.
Move the shaft left or right in the elongated slot in the pulley mounting bracket until a deflection of 1/2-inch is obtained.
Deflection measured with about 15 pounds of force at a point midway between fan pulley and belt tightener pulley.
Tighten nut securely.

Governor sensitivity adjustment adjustment

⚠ If the governor is too sensitive a rapid hunting condition occurs (alternate increasing and decreasing speed).

Turn the sensitivity adjusting ratchet accessible through a covered access hole on the side of the blower housing.
Radiator cooled: clockwise gives more sensitivity when full load is applied; counterclockwise gives less.
City water cooled: counterclockwise gives more sensitivity; clockwise gives less.
Adjust for maximum sensitivity without hunting, then readjust speed.
Replace the knockout plug in the blower housing and secure the speed stud lock nut.

Governor speed adjustment adjustment

Tools: Tachometer

Change spring tension by turning the governor spring nut.
Turn the nut clockwise (more spring tension) to increase RPM.
Turn counterclockwise to reduce governed speed.
Hold a tachometer against the flywheel cap screw.

Battery connection installation

⚠ Battery polarity must agree with the rectifier located in the control box. If battery ground must be changed, reverse the rectifier connection.

Connect battery positive (+) to starter engaging solenoid terminal post.
Connect battery negative (-) to a good ground on the engine.
Battery is connected for negative (-) ground.
For 24 volt cranking, provide two 12 volt batteries connected in series (one battery negative to the other battery positive).

Bleed air from fuel system maintenance

⚠ Crank engine one revolution if the camshaft pump lobe is up, to permit hand priming.

Disconnect the fuel return line.
Operate the hand priming lever on diaphragm type fuel transfer pump until no air bubbles in fuel flow from the return line fitting.
Connect the fuel return line.
Return priming lever to lowest (disengaged) position to permit normal pump operation.

Filling heat exchanger maintenance

⚠ After running unit 10 minutes the closed cooling system is pressurized and hot. Open the 14 pound pressure cap slowly to vent pressure.

Remove fill cap.
Open fill vent valve (turn counterclockwise).
Remove vent plug.
Fill with coolant until vents begin to overflow.
Close fill vent valve (turn clockwise).
Replace vent plug and fill cap.
Operate unit 10 minutes at full load and watch for leaks.
Shut down unit; slowly open pressure cap, check level, fill system to top with coolant.

Oil filter change maintenance

Place pan under old filter and remove by screwing counterclockwise.
Clean filter mounting area.
Install new filter, oil filter gasket and screw filter on clockwise until gasket touches mounting base.
Tighten 1/2 turn.

Out-of-service protection (more than 30 days) maintenance

⚠ Discharged batteries are subject to severe damage if exposed to freezing temperatures. Store all batteries fully charged.

Tools: Trickle charger

Run set until thoroughly warm; generator under at least 50 percent load.
Shut down engine and drain oil base while still warm; refill and attach a warning tag indicating viscosity of oil used.
Disconnect batteries and remove from vessel; maintain liquid level and use a trickle charger.
Provide a suitable cover for the entire unit.

Break-in procedure operation

⚠ Continuous running under one half load during the first few hundred hours usually results in poor piston ring seating, causing higher than normal oil consumption and blowby.

Run one half hour at 1/2 load.
Run one half hour at 3/4 load.
Run at full load.
Drain and replace the crankcase oil after 50 hours of operation; drain while the engine is still hot.

Returning the set to operation operation

⚠ Do not smoke while servicing batteries. Explosive gases are emitted from batteries in operation.

Tools: Hydrometer

Remove cover and all protective wrapping; remove plug from exhaust outlet.
Check warning tag on oil base and verify oil viscosity is correct for ambient temperature.
Clean and check battery; measure specific gravity (1.260 at 77 F [25 C]) and verify level at split ring.
Check that fuel lines and fittings are secure, without leaks.
Service cooling system with clean fresh water; prime water pump and bleed all air.
Connect batteries and verify no loads are connected to generator.
Start engine.
Check all gauges; unit is ready for service.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
110/190	3	12-lead broad range	T1 through T12
115/200	3	12-lead broad range	T1 through T12
120	1	2-wire service	T1 and T3 joined; T2 and T4 joined and grounded (white)	Ungrounded load wire (black)
120/208	3	12-lead broad range (Code 18R or 518R)	T1 through T12	Terminals V1, V2, V4
120/240	1	3-wire service	T1 and T4; T2 and T3; T0 center tap	Delta connected (60 hertz 120/240 volt model has code -50)
120/240	1	Code 3C or 53C reconnectible	T1, T2, T3, T4	Connect jumper W10 on the voltage regulator printed circuit board between terminal V4 (common) and V1, V2, or V3 as listed on the reconnection diagram.
127/220	3	12-lead broad range	T1 through T12
139/240	3	12-lead broad range	T1 through T12
220/380	3	12-lead broad range	T1 through T12
230/400	3	12-lead broad range	T1 through T12
240	1	2-wire service	T1 and T4 joined; T2 and T3 joined
240/416	3	12-lead broad range	T1 through T12
254/440	3	12-lead broad range	T1 through T12
277/480	3	12-lead broad range	T1 through T12
347/600	3	Code 9X prewired 4-wire	T1, T2, T3, T0	Special order 60 hertz generators prewired at factory

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Cummins/Onan RDJC family

Part #	Description	Category
140-0636	Element and Retainer, Air Cleaner	air_filter
300-1006	Board Assembly, Regulator	avr
305-0534	Regulator Assembly, Voltage (Complete)	avr
511-0066	Belt, Fan	belt
511-0067	Water Pump Belt Heat Exchanger Pump	belt
212-1064	Brush, Collector Ring	brush
122-0325	PRIMARY Fuel Filter Element	fuel_filter
122-0326	SECONDARY Fuel Filter Element	fuel_filter
149-0408	Filter, Secondary Fuel (Includes Cartridge)	fuel_filter
149-0428	Fuel Filter Element	fuel_filter
149-0846	Cartridge (For 149-1078 Filter)	fuel_filter
149-1078	Filter, Fuel - Mounted Between Fuel Tank and Transfer Pump	fuel_filter
149-1046	Repair Kit, Fuel Pump	fuel_pump
110-0546	Gasket, Glow Plug	gasket
110-1852	Gasket, Head	gasket
120-0580	Gasket Kit, Oil Pump	gasket
122-0188	Gasket, Filter Adapter	gasket
132-0072	Gasket, Water Pump Mounting	gasket
140-0584	Gasket, Air Cleaner	gasket
149-0455	Gasket, Secondary Filter - Cartridge to Head	gasket
149-0456	Gasket, Secondary Filter Bowl to Cover	gasket
149-0493	Gasket, Secondary Filter - Cartridge to Retainer	gasket
149-0517	Gasket, Fuel Pump Bowl	gasket
149-0792	Gasket, Fuel Pump Mounting	gasket
154-1057	Gasket, Exhaust Manifold	gasket
168-0100	Gasket Kit, Engine	gasket
309-0145	Gasket, Thermostat Cover / Thermostat Chamber	gasket
333-0106	Glow Plug (12 Volt)	glow_plug
503-0204	Hose, Radiator Curved	hose
503-0400	Hose, Radiator	hose
132-0114	Impeller	impeller
147-0043	Nozzle Only (Component of Nozzle & Holder Assembly)	injector
147-0044	Shield, Nozzle Heat (Steel)	injector
147-0136	Nozzle & Holder Assembly	injector
122-0185	Oil Filter	oil_filter
110-1221	Spring, Valve	other_service
110-1278	Valve, Exhaust (Stellite)	other_service
110-1320	Valve, Intake	other_service
110-1501	Guide, Valve	other_service
132-0111	Repair Kit	other_service
149-0463	Valve, Check	other_service
304-0500	Resistor, Tapped (Adjustable)	other_service
309-0169	1 Begin Spec G 25 26	other_service
333-0054	Heater, Water Jacket	other_service
522-0212	Overhaul Kit, Set	other_service
522-0264	Overhaul Kit, Set	other_service
120-0547	Pump Assembly, Oil	pump
132-0082	Repair Kit, Water Pump (Includes Shaft and Bearing, Impeller, Fan, Hub and Gasket)	pump
132-0105	Pump, Water (Spec A through C)	pump
132-0110	Fresh Water Pump - With Metal Impeller	pump
147-0231	Pump, Injection (Includes Buttons 2, 4, 11, 12, Retaining Ring, Injection Lines and Governor Linkage Ball Joint)	pump
147-0232	Pump, Injection (Includes Buttons 2, 4, 11, 12, Retaining Ring and Governor Linkage Ball Joint)	pump
149-1020	Pump, Fuel Transfer	pump
132-0101	Seal (captive water pump)	seal
509-0086	Seal, Oil - Rear Housing Plate	seal
509-0088	Seal, Governor Shaft	seal
509-0090	4 Seal, Oil Intake Valve (Includes Retaining Rings) 12	seal
130-0626	Zinc pencil anode for heat exchanger	sensor
193-0104	Sender, Water Temperature Gauge	sensor
193-0108	Sender, Oil Pressure Gauge	sensor
309-0178	'Switch, Thermostatic - Hi Engine Coolant Temperature	sensor
309-0179	'Switch, Thermostatic - Hi Engine Coolant Temperature	sensor
309-0130	Thermostat	thermostat

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

What is the oil capacity of the Cummins/Onan RDJC?

The Cummins/Onan RDJC engine has an oil capacity of 6.0 liters.

What is the displacement of the Cummins/Onan RDJC?

The Cummins/Onan RDJC has a displacement of 120.0 liters with 4 cylinders.

Which generators use the Cummins/Onan RDJC engine?

The Cummins/Onan RDJC powers 9 generator set(s), including Cummins/Onan 12.5RDJC-518R, Cummins/Onan 12.5RDJC-53CR, Cummins/Onan 12.5RDJC-57R, Cummins/Onan 15.0RDJC-18R, Cummins/Onan 15.0RDJC-3CR.

How often should you change the oil in the Cummins/Onan RDJC?

The Cummins/Onan RDJC oil change interval is every 100 hours.