1st Generation 5.9L Cummins Maintenance Guide & Parts List
How do I properly Maintain my 1st Gen 12V Cummins Pickup Truck?
If you’re reading this, it probably means you’re the proud owner of a 1989-1993 Dodge Ram D/W pickup truck. These trucks are the first generation of Dodge Ram Pickups available with a diesel engine. The diesel engine in these trucks is no ordinary engine however, they’re one of the most durable diesel engines ever built. Just because they have a reputation for durability, doesn’t mean that you should take a chance when it comes to proper maintenance though. With how easy it is to work on these trucks, there is no excuse for not taking care of one. I’ll cut you some slack though, it’s not easy finding the right parts and your truck might not have come with an owner’s manual. Don’t worry about it. You’ve come to the right place! We make taking care of your truck easy with our comprehensive 1st Generation 5.9L Cummins Maintenance guide.
Our 1st Gen 5.9L 12V maintenance guide gives you the proper service schedule to follow and detailed information pertaining to fluid capacities and specifications. We’ll even give you the exact parts you’ll need and links to where you can find them on Amazon. Assuming you have the parts you need at your home, you won’t have to go the store to pick anything up. All you need is a little bit of mechanical know-how and be willing to learn. If you need to learn a little bit before hand, spend a little time on Youtube. Changing fluids and filters is very easy, even for a beginner mechanic or a DIYer.

When Should I Service My Truck?
If you just bought your 12V Cummins, I would strongly recommend giving it a maintenance overhaul immediately. You don’t know how it was treated in the past. They could’ve worked the truck really hard or used it for work. If it’s a previous fleet vehicle, it probably wasn’t serviced as frequently as it should be. You also don’t know if the previous owner or the dealer you just bought it from used the proper fluids, filters, or engine oil. Don’t take the unnecessary risk! Just go ahead and service the truck as soon as you can.
If you’ve owned the truck for a while, maybe you’re just unsure of if you’ve been following the proper service schedule. Take a look at the mileage of your truck, and see where you’re at in comparison to the chart below. I recommend changing fluids every year or couple of years. Don’t be afraid of performing maintenance sooner than the mileage requirement. Fluids, oil, and parts can lose quality and degrade over time too. It’s better to perform maintenance too soon than being too late. Always keep in mind, the better you treat your truck, the better she will treat you.
What is the Correct 1st Generation 5.9L Cummins Service Schedule?
Follow the 1st Generation 5.9L Cummins maintenance schedule below like your life depends on it. Just remember, there are other parts that could fail that might need to be replaced too. Check out our section about things you should do every oil change to make sure you can catch problems like front end and steering problems early.
Normal Operating Conditions Service Schedule
Maintenance/Service | Miles | Kilometers | Months |
Change Oil | 6,000 miles | 9,600 km | 6 mo. |
Change Oil Filter | 6,000 miles | 9,600 km | 6 mo. |
Replace Fuel Filter | 12,000 miles | 19,200 km | 12 mo. |
Replace Engine Air Filter | Check Every Service interval, replace as necessary. | See Left | See Left |
Flush Cooling System (Initial flush) | 36,000 miles | 57,600 km | 36 mo. |
Flush Cooling System (After Initial flush) | 30,000 miles | 48,000 km | 24 mo. |
Drain & Re-Fill Automatic Transmission Fluid | 24,000 miles | 38,400 km | 24 mo. |
Replace automatic transmission Filter(s) | 24,000 miles | 38,400 km | 24 mo. |
Adjust Automatic Transmission Band | 24,000 miles | 38,400 km | 24 mo. |
Flush & Re-fill Manual Transmission Fluid | 60,000 miles | 96,000 km | 36 mo. |
Replace Transfer Case Fluid | 36,000 miles | 57,600 km | 36 mo. |
Adjust Valve Lash | 24,000 miles | 38,400 km | 24 mo. |
Replace Rear Differential Fluid | Not Specified by FCA, at least once every 100,000 miles or 5 years | See Left | See Left |
Replace Front Differential Fluid | Not Specified by FCA, at least once every 100,000 miles or 5 years | See Left | See Left |
Severe Operating Conditions Service Schedule
The following chart is the 1st Generation Cummins Maintenance schedule to follow if you frequently tow, idle, or drive in city conditions. If you use your truck for work, or if you beat on your truck, this is the First Gen Cummins service schedule for you.
Maintenance/Service | Miles | Kilometers |
Change Oil | 3,000 miles | 4,800 km |
Change Oil Filter | 3,000 miles | 4,800 km |
Replace Fuel Filter | 6,000 miles | 9,600 km |
Replace Engine Air Filter | Check Every Service interval, replace as necessary. | See Left |
Flush Cooling System (Initial flush) | 36,000 miles | 57,600 km |
Flush Cooling System (After Initial flush) | 30,000 miles | 48,000 km |
Drain & Re-Fill Automatic Transmission Fluid | 12,000 miles | 19,200 km |
Replace automatic transmission Filter(s) | 12,000 miles | 19,200 km |
Adjust Automatic Transmission Band | 24,000 miles | 38,400 km |
Flush & Re-fill Manual Transmission Fluid | 60,000 miles | 96,000 km |
Replace Transfer Case Fluid | 36,000 miles | 57,600 km |
Adjust Valve Lash | 24,000 miles | 38,400 km |
Replace Rear Differential Fluid | 12,000 miles | 19,200 Km |
Replace Front Differential Fluid | 12,000 miles | 19,200 Km |
1st Generation Cummins Fluid Capacity
Another important factor in first generation Cummins maintenance is fluid capacity. You want to make sure you know how much fluid or oil you need to purchase before servicing your truck. The last thing you want to do is drain your truck of fluid or oil, only to find out you didn’t buy enough to properly re-fill your truck. Take a look at our 1st Gen 5.9L Cummins Fluid Capacity chart below.
Oil/Fluid | Capacity – Quarts | Capacity – Liters |
Engine Oil /w Filter | 12 Quarts | 11.4 Liters |
Auto Transmission Fluid 47 RE/RH ————– A727 | See Below 4 Quarts Service Refill 14.5-16.5 Quarts dry refill 11 Quarts | See Below 3.8 Liters 8.2-15.6 Liters 10.4 Liters |
Manual Transmission Fluid Getrag G360 NV4500 | See Below 3.5 Quarts 4 Quarts | See Below 3.3 Liters 3.8 Liters |
Transfer Case NP205 NP231 NP231HD NP241 NP241HD | See Below 2.22 Quarts 1.25 Quarts 1.25 Quarts 2.4 Quarts 3.25 Quarts | See Below 2.1 Liters 1.2 Liters 1.2 Liters 2.2 Liters 3.1 Liters |
Coolant | 24-26 Quarts | 22.7-24.5 Liters |
Front Differential Fluid Dana 60 | See Below 3.15 Quarts | See Below 3 Liters |
Rear Differential Fluid 2WD Dana 70 4WD Dana 70 2WD Dana 80 4WD Dana 80 | See Below 3.5 Quarts 3.9 Quarts 3.4 Quarts 5 Quarts | See Below 3.3 Liters 3.6 Liters 3.2 Liters 4.8 Liters |
1st Gen Cummins Maintenance Parts
Using high quality parts, filters, and fluids is so important in proper 1st Generation Cummins Maintenance. Finding the best parts and fluids to use is difficult because the 1st gen Cummins is old. To make it easy on our readers and fellow diesel lovers, we compiled a list of the most common first gen Cummins maintenance parts. Take a look at the chart below. Click on the links below if you’d like to purchase the parts from Amazon! The prices are great and the shipping is awesome for Amazon Prime members.
Part Type | Part # | Amazon Link |
Engine Oil | 15W40 | Shell Rotella T4 15W40 Shell Rotella T5 (blend ) 15W40 Shell Rotella T6 15W40 |
Engine Oil Filter | LF16035 LF3972 | Fleetguard Stratopore LF16035 Fleetguard LF3972 |
Fuel Filter | FS1232 FS1251 | – Fleetguard FS1232 (/W Water/Fuel Sensor) – Fleetguard FS1251 (No Water/Fuel Sensor |
Engine Air Filter ’89-’92 ’93 | Years AF4555M AF25023 | Filters Fleetguard AF4555M Fleetguard AF25023 |
Coolant | N/A | 50-50 Mixture of Distilled Water and glycol ethylene coolant |
Automatic Transmission Fluid | ATF+4 | Mopar ATF+4 |
Manual Transmission Fluid | 5W30 Engine Oil | 5W30 Motor Oil |
Serpentine Belts Intercooled /w AC Non-Intercooled /w AC Intercooled No AC Non-Intercooled No AC | See Below K080830HD K080816HD K080635 K080645 | See Below Gates K080830HD (‘91.5-’93) Gates K080816HD (’89-’91) Gates K080635 (‘91.5-’93) Gates K080645 (’89-’91) |
Upper Radiator Hose 89-91 Non-Intercooled ‘91.5-’93 Intercooled | See Below 20957 21930 | See Below Gates 20957 Gates 21930 |
Lower Radiator Hose | 20431 | Gates 20431 |
Transfer Case Fluid | ATF4+ | Mopar ATF+4 |
Front Differential Fluid | SAE 80W-90 | SAE 80W-90 |
Rear Differential Fluid | SAE 80W-90 | SAE 80W-90 |
Learn More About the First Generation Cummins
Click on one of the links below to view some of our other first generation Dodge Cummins diesel resources.
- 1st Gen 5.9L Cummins Specs
- 7 Most Common First Gen 5.9L Cummins Problems
- Best 1st Generation Cummins Upgrades