Troubleshooter: What to know when considering a small diesel for your next truck

Fuel costs

The fuel economy gains of diesels over gasoline can be wiped out by price differences between the two fuels at the pumps. While you may get 20-25% more fuel economy with a diesel compared to a petrol with the same power on paper, if you pay 20-25% more at the pumps, those savings disappear. And when you consider the premium that diesels carry over their sticker price, don’t expect diesels to save you money on acquisition or operating costs, no matter how long you own one.

Diesel exhaust fluid

Adding diesel to the DEF system is just as bad, although slightly cheaper to repair. If a DEF system develops an error, a countdown screen will appear in the dash. While gasoline engines can simply illuminate the check engine light and let you go on your way when an emissions failure occurs, leaving a modern diesel’s countdown to zero unfixed the problem will prevent the engine from starting. Many of these systems are so delicate that even filling your truck’s DEF through a funnel that has a few milligrams of old motor oil stuck to it could cause a related check engine light to appear. the DEF and start the timer.

Oil changes are usually more expensive for a modern diesel as they require special synthetic oil. Many new gas engines also require synthetic oil to maintain factory warranties, but small-displacement diesel oil changes can cost $250-$300, while most gas services stay under $200.

Exhaust regeneration

Regeneration sounds like a friendly, eco-friendly term, but with a modern diesel, it’s something else. Diesel exhaust systems contain a particulate filter and a catalytic converter. When the filter is full (depending on the sensors installed) a regeneration cycle starts. The engine computer commands a very rich fuel mixture, so rich that the unburned liquid fuel is poured into the exhaust system to burn inside the particulate filter and clean up the accumulated particles. The owner’s manuals have all kinds of warnings about not parking the vehicle near flammables after this, as the exhaust will remain very hot for a while. They will also mention the need to make sure you have at least half a tank of fuel. Regen frequency will depend on usage, but if you’re regularly in slow, stop-and-start traffic, this may happen more often. Cycles can take anywhere from 20 minutes to several hours, depending on engine speed, load, and amount of soot build-up, and fuel economy will be off while they occur.

Sometimes these filters become too clogged to clear a regeneration cycle. Diesel particulate filters are expensive to replace, often costing more than $2,000 for the part alone. Fortunately, several companies have sprung up that offer cleaning services at a fraction of the cost of replacement, and auto parts store shelves are stocked with a selection of fuel additives to help the process without having to remove the filter

Running out of fuel

Running out of fuel with a gasoline engine is usually the least inconvenience of a trip to the gas station, can in hand. But with a diesel, there’s often a bit more to making sure the lines feeding the injectors are full of fuel with no air bubbles along the way.

This usually means running the engine a little longer after adding fuel to the tank. Some diesel veterans will tell you that partially opening the fittings on those fuel lines can help clear the air faster, but with a small modern diesel, don’t let anyone try that trick. Many of these lines are disposable, meaning that if someone loosens a fitting, the lines must be replaced.

Whether these little diesels will live up to the longevity reputation of their bigger cousins ​​is yet to be seen, especially given their relatively short time on the market. If you’re focused on towing capacity and payload, remember that these limits are primarily based on axle strength, and all of the Detroit Three offer gasoline engines in their half-ton trucks that will match their axle weights and towing ratings.