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It’s important for any vehicle to be properly maintained if you want to maximize its lifespan and reliability.
However, taking care of a diesel truck has its own unique requirements compared to gas trucks. Certain maintenance tasks for diesel trucks must be performed on a regular basis or you will significantly shorten the life of your engine.
Note: capacities vary greatly so it is a good idea to research what you have and how much fluid you’ll need. You can typically find this information online or in your owner’s manual.
Let’s take a look at some crucial engine maintenance for your diesel truck.
Diesel trucks are different from gas trucks in that they have larger oiling systems that let them go longer between changes. In fact, the oil change frequency for diesel trucks is largely dependent on the exact make and model of your vehicle as well as how you use it.
For example, the 6.0L Powerstroke is very susceptible to oil contamination and should have its oil changed every 3,000 to 5,000 miles.
Newer common-rail diesel engines that burn a lot cleaner can often extend oil life to 7,000 or 10,000 miles.
*Note* – The engine oil we provide is in compliance with the requirements of the manufacturer’s OE specs and approvals.
Here’s the common schedule for some popular diesel engines:
Gear oil is an oft-forgotten part of diesel maintenance. It’s one of the most neglected fluids simply because it’s rarely changed in lighter-duty vehicles. However, diesel trucks typically do a lot of heavy work.
Gear oil should thus be changed every 20,000 miles of heavy towing. It should be changed about every 50,000 miles of mixed-use driving.
*Note* – The gear oil we provide is in compliance with the requirements of the manufacturer’s OE specs and approvals.
However, this can vary by the engine as follows:
| Maintenance Schedule Interval | Maintenance Supplies Available |
| 1989-1993 5.9L 12V Cummins every 15,000 miles | 1989-1993 5.9 Cummins Differential Service Kit |
| 1994-1998 5.9L 12V Cummins every 15,000 miles | 1994-1998 5.9 Cummins Differential Service Kit |
| 1998.5-2002 5.9L 24V Cummins every 15,000 miles | 1998.5-2002 5.9 Cummins Differential Service Kit |
| 2003-2004 5.9L 24V Cummins every 15,000 miles | 2003-2004 5.9 Cummins Differential Service Kit |
| 2004.5-2007 5.9L 24V Cummins every 15,000 miles | 2004.5-2007 5.9 Cummins Differential Service Kit |
| 2007.5-2012 6.7L 24V Cummins every 15,000 miles | 2007.5-2012 6.7 Cummins Differential Service Kit |
| 2013-2022 6.7L 24V Cummins every 15,000 miles | 2013-2022 6.7 Cummins Differential Service Kit |
| 6.6L Duramax LB7 every 50,000 miles | 6.6 Duramax LB7 Differential Service Kit |
| 6.6L Duramax LLY every 50,000 miles | 6.6 Duramax LLY Differential Service Kit |
| 6.6L Duramax LBZ every 50,000 miles | 6.6 Duramax LBZ Differential Service Kit |
| 6.6L Duramax LMM every 50,000 miles | 6.6 Duramax LMM Differential Service Kit |
| 6.6L Duramax LML every 50,000 miles | 6.6 Duramax LML Differential Service Kit |
| 6.6L Duramax L5P every 50,000 miles | 6.6 Duramax L5P Differential Service Kit |
| 7.3L Powerstroke every 100,000 miles normal use and 30,000 miles for severe use | 7.3 Powerstroke Differential Service Kit |
| 6.0L Powerstroke every 97,500 miles | 6.0 Powerstroke Differential Service Kit |
| 6.4L Powerstroke every 50,000 miles for severe use, but otherwise only if there’s a leak | 6.4 Powerstroke Differential Service Kit |
| 6.7L Powerstroke every 150,000 miles under normal conditions 50,000 miles under severe duty conditions | 6.7 Powerstroke Differential Service Kit |
Vehicles with 6.7L Cummins were equipped with various differential options from LSD (limited slip differential) to non-LSD, tall ratio to short ratio etc. All these units work very hard in a heavy truck that is destined for even harder use.
There were many variations that a vehicle could be ordered with, good news is that we have every fluid available to service nearly every single differential.
Modern diesel engines run quite hot thanks to exhaust gas recirculation, which is an emissions requirement. EGR is very hard on coolant, so it’s essential to keep a regular eye on your coolant to make sure that it is still protecting your engine.
The following flush intervals are recommended for specific engines:
| Maintenance Schedule Interval | Maintenance Supplies Available |
| 1989-1993 5.9L 12V Cummins every 24,000 miles | 1989-1993 5.9 Cummins Coolant |
| 1994-1998 5.9L 12V Cummins every 24,000 miles | 1994-1998 5.9 Cummins Coolant |
| 1998.5-2002 5.9L 24V Cummins every 24,000 miles | 1998.5-2002 5.9 Cummins Coolant |
| 2003-2004 5.9L 24V Cummins every 24,000 miles | 2003-2004 5.9 Cummins Coolant |
| 2004.5-2007 5.9L 24V Cummins every 24,000 miles | 2004.5-2007 5.9 Cummins Coolant |
| 2007.5-2012 6.7L 24V Cummins every 100,000 miles or 60 months | 2007.5-2012 6.7 Cummins Coolant |
| 2013-2022 6.7L 24V Cummins every 100,000 miles or 60 months | 2013-2022 6.7 Cummins Coolant |
| 6.6L Duramax LB7 every 150,000 miles | 6.6 Duramax LB7 Coolant |
| 6.6L Duramax LLY every 150,000 miles | 6.6 Duramax LLY Coolant |
| 6.6L Duramax LBZ every 150,000 miles | 6.6 Duramax LBZ Coolant |
| 6.6L Duramax LMM every 150,000 miles | 6.6 Duramax LMM Coolant |
| 6.6L Duramax LML every 150,000 miles | 6.6 Duramax LML Coolant |
| 6.6L Duramax L5P every 150,000 miles | 6.6 Duramax L5P Coolant |
| 7.3L Powerstroke every 15,000 miles | 7.3 Powerstroke Coolant |
| 6.0L Powerstroke every 45,000 miles | 6.0 Powerstroke Coolant |
| 6.4L Powerstroke every 50,000 miles | 6.4 Powerstroke Coolant |
| 6.7L Powerstroke every 45,000 miles | 6.7 Powerstroke Coolant |
Transmission fluid has seen a lot of advancements just like other fluids, which means that change intervals are longer than before. However, diesel enthusiasts almost never leave their engines stock, so the horsepower gains will reduce transmission fluid life.
*Note* – The transmission oil we provide is in compliance with the requirements of the manufacturer’s OE specs and approvals.
The following are some transmission fluid change intervals for different engines:
You might be wondering why fuel is included here with the fuel filter. In some cases, you might have to drain your tank and refuel. Moisture in diesel fuel is very bad for the engine, and it can get in when you least expect it.
A good rule of thumb is to always use a high-traffic gas station to get a good batch of gas. Fuel that sits too long underground can accumulate moisture.
If these intervals seem a lot shorter than gas engines, they definitely are. Diesel engine fuel filters get dirty a lot faster.
For fuel filters, consider the following intervals:
Brake fluid degrades over time due to its hygroscopic quality, which means that it easily attracts moisture like a sponge. If there’s moisture in your brake fluid, that means that the boiling point will be lowered. The heat that goes through your brake system is plenty to boil old brake fluid.
Having degraded brake fluid in your system can be a safety issue, especially if you tow. Check your specific manual for the recommended intervals to flush and replace brake fluid. A common interval is every 24 months.
According to recommended service intervals for Powerstroke, Cummins, and Duramax diesel engines, brake fluid and power steering fluid should be checked during every service and flushed and replaced as necessary.
For the DIY mechanic, it’s essential to have a good stock of shop supplies on hand to assist in your maintenance and repair tasks. Some common shop supplies that work for many repair and maintenance applications include the following:
Most of these items are very necessary for many routine maintenance jobs. For example, WD40 can be used to lubricate bolt holes, as a rust inhibitor, and to unstick locks, among other applications. It’s definitely a DIY shop must-have.
Keeping up on your truck’s fluids is a great start to increasing the lifespan of your engine. If you have a 4WD truck, you generally also want to change the transfer case fluid every 60,000 to 100,000 miles.
However, if you don’t use 4WD much, some trucks can definitely go much longer. It’s a good idea to perform a maintenance check every 10,000 miles or 12 months, whichever comes sooner.
Your air filters will likely need to be changed at this point. One thing to understand about diesel trucks is that diesel fuel is a dirty-burning fuel.
Checking up on your engine regularly is mainly to make sure that it’s staying clean. If you can keep your engine as clean as possible, you will increase its life expectancy significantly.
Hopefully, with regular maintenance, you won’t run into any of these problems very often. However, diesel parts can also fail unexpectedly. Here are a few trouble signs to keep an eye out for:
Rely on ProSource Diesel to repair or replace your diesel engine parts, including Cummins parts, Duramax parts, and Powerstroke parts. We sell a wide selection of aftermarket and OEM parts to keep your diesel engine running great for a long time.
