How To Make Your Diesel Engine Last As Long As Possible

Dec 14, 2023

It used to be all you had to do was keep fuel in the tank, change the oil every once in a while and your diesel would always take care of you. At least it seemed that way… Then the torque war between the Big Three took over and the EPA began to ramp up emission standards. Then when keeping up with the Joneses (i.e. OEM's playing cat-and-mouse with horsepower and torque ratings) crossed paths with meeting ever-tightening NOx and particulate matter emissions—two pollutants that for all intents and purposes feed off of each other—reliability and fuel economy were sacrificed, at least to an extent.

So how exactly do you make a diesel-powered truck last as long as possible in the modern age? It starts with the basics of vehicle maintenance, not skimping on replacement parts and understanding how your emissions control system works. The tips offered below will give you and your compression-ignition companion the best chance of hanging in there for the long-haul.

Stick with factory components, fluids and filters. Think about it. The original manufacturer spent millions upon millions of dollars engineering an engine to run on a certain oil, breathe through a certain air filter and keep its fluids free of debris using specific oil and fuel filters. Once you venture outside of those OE components you’re basically your own R&D department—plus you could be denied a warranty claim in the event of a catastrophic engine failure. Think about that. Also make sure to observe recommended emissions system cleanings if they apply. We’ll touch on this a little more below.

Yes, today's ultra low sulfur diesel (ULSD) isn't the best fuel in the world, but if your engine was produced in the ’06 time frame or later it was designed to run on it perfectly fine. The trick is to make sure you’re pumping the highest quality fuel you can find into your tank. That means visiting high-traffic filling stations that move a lot of diesel in and out on a regular basis. Within a matter of just four weeks after being refined, diesel fuel can degrade as much as 26-percent. Trust us, quality fuel from a highly-frequented filling station will be some of the best quality and cleanest fuel you can find, and it will help prolong the life of your injectors and injection pump, neither of which are cheap to replace. Fuel additives help as well, but that's a loaded conversation and a story for another time.

Ever wonder why we don't bother to clean all the grime off the end of the diesel pump nozzle? The OE's count on debris and contaminants making it into the tank. It's up to the water separator and fuel filter to keep the fuel headed to the injection pump and injectors clean. That's why, beyond topping off at a reputable filling station, observing fuel filter changes at the recommended interval is so important. Never stretch fuel filter changes and (as mentioned) stick with OEM replacements. The average modern era common-rail diesel system runs $6,000 to $10,000 to replace…

It's elementary, right? Change the oil at the recommended mileage interval with the correct oil and filter and you’re good to go. However, there is often more to it than meets the eye in the diesel world. Work trucks first and foremost, a lot of diesels spend inordinate amounts of time idling. But zero miles driven doesn't equate to zero wear and tear on the engine oil. In fact, one hour of idle time is equal to roughly 25 miles driven. If your engine idles a lot, make sure you factor that time into your oil change schedule or you’ll be way over on engine hours—even if the odometer only says you’ve traveled 5,000 miles…

The life of an engine's air filter is much easier in a road-bound application. But even in these conditions, the air filter should still be inspected at each oil change, along with the owner keeping tabs on the filter minder (if applicable). For engines that live in the field or that see dust on a regular basis, more attention should be paid to the air filter element's cleanliness. Remember that the last line of defense in protecting the turbocharger's compressor wheel is the air filter—and turbos aren't cheap to replace. Also know that the number one cause of turbo failure is debris ingestion due to a dirty air filter… If you have an aftermarket, cleanable filter that's fine, but keep tabs on it. As a general rule of thumb for trucks on the pavement, don't go more than two years without replacing the air filter element or cleaning it.

This is a dark gray area, but one that has to be discussed if we’re being honest about making a modern diesel engine last. To answer the question many first time diesel buyers ask, yes, emissions control devices such as EGR coolers and valves, DPF's, diesel oxidation catalysts and SCR/DEF systems are problematic—along with all the sensors that go along with them. And yes, they are detrimental over time to engine performance, require precise and timely maintenance and can cause you some downtime every once in a while. There are aftermarket solutions to all of the above, but we’ll leave that between you and your specific dealer or independent mechanic. If you choose to live with the factory emissions controls, double-check for any cleaning intervals that can be observed, such as the 67,500-mile EGR valve and cooler cleaning recommended by Cummins on all ’07.5-‘21 6.7L engines.

As proof that late-model diesels can still go the distance, look no further than the picture above. The 6.6L LMM Duramax V-8 on the other end of this odometer was anything but on its last leg. In fact, it barely had any blow-by. It spent all of its 600,000 miles towing campers across the U.S. The trick was an uncompromising maintenance regimen, fill-ups at high-traffic stations and low rpm cruising. The Chevrolet Silverado 3500 took its time, often hanging around in the right lane at 65 mph and with the Duramax turning 1,700 to 2,000 rpm. Of course, normal wear items such as U-joints, a few unit bearings and brakes needed replacing, but the rotating assembly has never been touched. The truck would go on to accumulate more than 740,000 miles before being traded in for a new one.

The 6.0L Power Stroke was the worst diesel engine ever produced, right? Blasphemy. While there is no denying their well-documented problems, we’ve seen loads of ’03-’07 Super Duty's with 250,000 miles or more on the odometer. On top of that, we were once towed home by a bone-stock 6.0L Power Stroke that had never blown a head gasket, experienced a failed EGR cooler or stuck EGR valve and that had never even gone through a single oil cooler.