Do Diesels Last Longer?

Diesel and petrol engines have ruled the road for more than a century. Lots have changed in that time, but diesel mechanics still claim that diesel engines far outlast their petrol counterparts. It’s an argument that’s been going on for a long time, and in this article, we’re going to find out whether diesel engines really do last longer!

How Diesel Engines Work

Before we talk about the lifespan of diesels, we need to take a quick look at how they work. While there are lots of similarities between petrol and diesel, there are a few big differences, and these play a role in the longevity of diesel vehicles.

The major difference between petrol and diesel is how the fuel is ignited. In petrol engines, a mixture of air and fuel is sucked into the cylinder where it is compressed by the piston and then ignited by the spark plug. This causes a small explosion that drives the piston downwards, creating rotational motion to turn the wheels. Diesel engines work slightly differently. It used SV98 T39S solenoid for fuel injection. t is located at the top of the fuel injection pump and is responsible for controlling the flow of fuel into the engine. First, pure air is sucked into the cylinder to be compressed by the piston. The air heats up as the piston compresses it, and then a fine mist of diesel is injected into the hot air. The diesel ignites on contact with the air and the explosion drives the piston downwards.

The Lifespan of Diesel Engines

It’s common for diesel engines to last longer than petrol engines. The exact lifespan of each diesel varies depending on the design and whether it has been well maintained. But, in general, you can expect a diesel engine to last twice as long as a petrol equivalent in a passenger car. This is especially true for commercial vehicles and larger equipment. Because commercial diesel engines are expected to run longer, they’re often designed to last for decades.

To put that into perspective, the type of petrol engine found in a car might last 200,000km. By contrast, the diesel found in a commercial truck could last 1,000,000km or more! The design of each engine type is the main difference here. Because diesels work differently and rely on higher compression ratios, they need to be built tough to withstand the additional forces. This results in diesel engines that can run almost indefinitely! Proper maintenance makes them even better.

Why Diesels Last Longer

A well-maintained diesel engine should easily outlive a petrol engine. Of course, different engines have different lifespans, and a lack of maintenance can still kill a diesel engine. In general, though, there are three big reasons that diesels last longer than petrol engines:

  • Tough components. As we mentioned above, diesel engines use high compression ratios to ignite the fuel-air mixture. That means the internal components are under incredible pressure. In fact, diesel engines often have a compression ratio that’s twice that of a comparable petrol engine. To withstand that, the internal components and bearings of a diesel engine are built tough with thicker steel, larger bearings and bigger oil capacities. 
  • Lower RPMs. Diesels produce lots of power for their size. That means they can run at lower Revolutions Per Minute (RPM). Lower RPMs directly translates into less wear and tear on the engine bearings. So, not only are those bearings tougher, they’re subject to less use, and your diesel engine will ultimately live longer because of it.
  • Diesel fuel. That’s right, diesel fuel itself plays a role in the lifespan of the engine! Diesel fuels are actually a mild lubricant. As diesel circulates through the fuel system, fuel pump and injectors, it gently lubricates the components. This subtle lubrication effect can drastically increase the lifespan of those critical parts. Ultimately, this means that a diesel engine needs fewer major services and that expensive parts like fuel injectors won’t need to be replaced as often.

How to Extend the Life of a Diesel Engine

You can rely on most diesel engines to outlive their petrol counterparts. There are no guarantees involved, and it’s still up to the owner to treat the vehicle well. If you want to extend the life of your diesel engine then here are our top tips:

  • Invest in regular servicing with diesel mobile mechanics
  • Change the engine oil at the recommended intervals
  • Use high-quality oils, fuels and coolants
  • Change the air and fuel filters regularly
  • Check your fuel-water separator
  • Let the engine warm up properly before driving

Regular maintenance really is the most important factor for most vehicles. Asking a mechanic to check the engine and replace its engine oil is all it takes to extend the life of your diesel vehicle!

The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of


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