Do Diesel Engines Last Longer?

Diesel vs petrol engines is a debate that’s been raging for almost a century. While the two types of engines share lots of similarities, the way they use and burn fuel means they’re suited to very different purposes. Diesel engines are often found in heavy duty commercial equipment where they’re expected to run continuously and work long hours. To ensure they stand up to those harsh conditions, diesel engines are built tough, and that means their lifespan is hard to beat. So, do diesel engines last longer than petrol? In this article we’re going to find out!

Do Diesel Engines Last Longer?

Diesel engines often last much longer than petrol engines. The two technologies are similar, but differences in design mean that diesel engines are built tougher and last longer. This is true for all types of passenger cars, trucks, commercial vehicles and other diesel-powered equipment. Like all engines, diesels only last a long time if they’re looked after properly. Investing in regular maintenance, oil designed for diesel engines, fuel additives and high quality coolant are all simple ways to prolong the life of a diesel engine.

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Why Do Diesel Engines Last Longer?

Diesel and petrol engines work similarly, but there are a few key differences between the two technologies. Why do diesel engines last longer? There are three major reasons:

  • Toughened engine components. Diesels typically feature bigger pistons, longer stroke length and higher compression. This means that diesels produce more torque than petrol engines, and it also means the components need to be strengthened. To put up with the extra power, diesels are assembled using heavy duty parts and bearings that last far longer than their petrol counterparts.
  • Diesel fuel is a lubricant. Diesel fuel actually acts as a mild lubricant as it travels through the fuel system, through the injectors and into the cylinder. Compared to petrol which is actually a solvent, diesel can dramatically prolong the life of the vehicle’s fuel system.
  • Low RPMs. Diesel is more energy-dense than petrol. That means a diesel engine can output the same amount of power at lower RPM (revolutions per minute). Fewer revolutions means less wear and tear on engine components like piston rings, crank bearings and valve seals, which can greatly extend the engine’s life.

How Much Longer Do Diesel Engines Last?

It’s common for diesel engines to last far longer than petrol engines, with some diesels living for 1,000,000 kilometres or more. By contrast, the petrol engines found in passenger cars typically only last for 200,000 kilometres before requiring a major overhaul.

Tips to Prolong the Life of Your Diesel Engine

So, diesel engines last much longer than petrol alternatives, but that doesn’t mean they last forever. Like any other engine, diesels need maintenance, and hard use wears down critical components, causing the engine to fail. If you want to prolong the life of your diesel engine, we have a few simple tips:

  • Invest in regular servicing and preventative maintenance
  • Use high quality engine oils designed for diesels
  • Regularly check your fuel-water separator
  • Change your fuel filter
  • Replace your air filter regularly
  • Keep your RPMs low and avoid over-revving the engine
  • Let the engine warm up to operating temperature before putting it under load

Diesels produce a lot of power for their size. That means the internal components are built to exacting standards. The best way to extend the life of a diesel engine is to regularly change the oil and check the fuel. Degrading engine oil and contaminated fuel are two of the biggest killers of diesel engines, so staying on top of those issues can help you avoid the worst!


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