How To Drive (& Maintain) a Diesel Car to Prevent Engine Problems

I’ve been inspired to write this article after a friend, a mechanic from Zagreb, Croatia, called me up about the massive troubles they are seeing on inner-city driven diesel cars.

Seeing 2-year-old diesel cars with less than 40,000 kilometers (ca. 25,000 miles) on the odometer needing a complete carbon cleaning and EGR valve replacements is crazy. A healthy diesel engine should have no problems reaching 200,000 kilometers (ca. 120,000 miles) with nothing but regular oil and filter changes.

So who’s at fault? Well, both the owner and the car salesman that doesn’t instruct the buyers about the purpose of a diesel engine. If you’re looking for a city commuter, a big diesel engine is hardly the right option.

People just love their diesels, especially in Europe, they are tricked into buying them due to the incredible fuel economy, but they are soon left disappointed once issues arise.

Here are is how you should drive and maintain a diesel engine if you want to keep it healthy & problem free for the years to come.

How to Prevent Diesel Engine Problems

Here are the 10 things any diesel car owner should do to prevent engine problems:

  1. Do not leave your diesel engine running.
  2. Allow the pre-heating glow plugs to finish their work.
  3. Allow your diesel engine to warm up.
  4. Use only the proper oil and high-quality diesel fuel.
  5. Diesels are designed to be driven on long distances.
  6. Always keep an eye on the engine oil level.
  7. Don’t always run your diesel at the bare minimum of fuel.
  8. By doing so, you can avoid carbon buildup and DPF clogging.
  9. Look for any oil leaks on or around the engine.
  10. Allow your diesel engine to idle for a minute before turning it off.

Doing these things will prevent at least 60% of the common diesel engine problems that aren’t exactly cheap to repair. As we continue, we’ll describe each issue in detail and support our claims with personal experience and proof.

Do not leave your diesel idling

We’re kicking things off with this seemingly innocent habit that everyone does. How can leaving your diesel to idle and warm up cause trouble, seems weird, doesn’t it.

Many people ask themselves “what does prolonged idling to do a diesel engine?” and it’s a fair question.

Prolonged idling wastes fuel, causes increased engine wear, it accumulates soot in your intake manifold, and it can lead to fuel dilution (trust me, I’ve been there with my OM642 Mercedes diesel engine).

If you don’t believe us that this is bad, check out this research from the Oak Ridge National Laboratory on car manufacturers guidelines on prolonged engine idling. If you take a peek at an article on my personal experience with engine oil fuel dilution, you can also see a direct screenshot from Mercedes confirming that prolonged idling does cause oil dilution problems (amongst other things).

Almost every single car manufacturer advises against prolonged idling. What you should do instead is just take it easy. You can leave the car idling for 30 seconds so the engine gets lubricated and then just take off and take it easy for the first 10-15 minutes.

That’s it, don’t leave your diesel idling, your neighbors, and your engine are going to love you for it!

Wait for the pre-heating glow plugs to do their job

All modern diesel engines come with glow plugs. The purpose of a glow plug is to heat up the incoming mixture of air and fuel to ensure the combustion process ignites your engine without misfiring or choking.

It is a crucial component of any diesel engine as it helps the engine to start up, especially in cold weather.

This process is usually indicated on your dashboard with an orange curvy wire glow plug warning light. As long as that light is shining, you should not power up the engine. This usually takes less than 5 seconds.

glow plug diesel symbol
The glow plug warning light should look like this, but orange.

Once the glow plug warning light disappears, it’s time to power up and drive away, your diesel engine is ready to go.

Give your diesel engine the time to warm up

This one is crucial. Diesels are sensitive souls when it comes to operating temperatures. Cold diesel engines need to be driven with ease. They usually take a bit more time to warm up than petrol engines, but that’s just how things are.

Revving up and driving a diesel engine hard when it’s cold is a sure way to cause severe engine wear in the long run. Driving a cold diesel engine like a maniac will also lead to timing chain wear and stretching.

As we’ve learned before, you should not let your diesel engine idle to warm up, you should just drive it with ease until it warms up to its ideal operating temperature. Consult your owner’s manual to see what that temperature is for your specific engine.

Once it reaches that temperature, give it hell, rev that engine up! Diesel engines need to be driven hard when they are warmed up, it’s the best way to clear up any soot/carbon deposits and to clear out your diesel particulate filter!

Only use the appropriate oil and high quality diesel fuel

Modern diesel engines are nothing like those bulletproof diesel from the 1990s. You could literally pour filtered vegetable oil down the fuel tank and your engine wouldn’t mind.

Todays diesel engines however are extremely sensitive to both appropriate oil and high quality diesel fuel. Make sure you only use the engine oil prescribed by your car manufacturer.

Unless there are clear problems, we don’t recommend switching to a thinner oil (like 5W30) during the winter. Your engine manufacturer knows which oil is best, so stick to it.

Fuel injectors in modern diesel engines are extremely sensitive, so make sure you don’t fuel up with bootleg diesel that you bought from your neighbor. Trust us, suffering from fuel injector problems is not a fun ordeal.

Diesels are meant to be driven on long journeys

Repeat after us: “Diesels are not meant for short commutes”. This is the number 1 diesel engine killer that causes numerous problems, begining with carbon build up, oil dilution and DPF filter blockages. We’ve recently talked about diesel AdBlue SCR system problems, and there’s direct correlation between short commutes and AdBlue problems.

There’s nothing wrong if you make the occasional short trip with a diesel, but it’s crucial you don’t use your diesel for short trips only.

We’ve seen numerous diesel cars with less than 60,000 miles on the clock with completely clogged up EGR valves, intake manifolds and valve seats. Cleaning out a sooted up engine is no joke. It’s labor intensive and costly.

Keep an eye on the engine oil level at all times

All diesel engines burn a certain amount of engine oil as part of normal engine operation. This can be a problem for modern diesel engines as excessive oil consumption can lead to permanent DPF clogging.

The other issue we mentioned earlier is fuel dilution. Fuel dilution can occur as a consequence of wet stacking and excessive idling. The culprit behind increased engine oil levels can also be leaky fuel injectors and poor overall maintenance.

To make sure everything is running as it should, you should make a habit of regularly checking your engine oil levels. It only takes a minute, but it can literally save your engine if you notice first signs of problems.

To learn what is considered to be normal diesel engine oil consumption, you can trust Valvoline’s guide.

Don’t run your diesel at the minimum fuel levels

This one is debatable, but it’s an issue that affects the majority of diesel engines with DPF filters. Constantly running low on gas can prevent your diesel engine from triggering the DPF filter regeneration process.

This is certainly true for BlueTec Mercedes engines. They prevent the DPF regeneration process if there’s less than a quarter of diesel in the fuel tank. Keep this in mind!

Avoid carbon buildup and DPF clogging by doing this

My mechanic once told me: “Wait till it’s warmed up, then let it loose and it’ll run forever”! And he couldn’t be more right. It’s essential to let your diesel fully warm up to it’s operating temperature.

Once it’s warmed up, you’re more than welcome to enjoy all the torque and horspower your diesel is giving you. By revving it up and driving it with some force, you’ll ensure that carbon deposits fly right through your engine, without forming harmful deposits.

The same is true for the state of your DPF filter. Really heating up your exhaust and driving for prolonged periods of time will ensure your DPF filters stays clear and healthy.

Keep an eye out for any oil leaks

Due to a higher compression ratio in the engine, it’s a lot more common to see diesel engine leak oil sooner than on their petrol counterparts. Keep an eye around the engine, mainly around all the rubber seals and gaskets. You might also see oil leaks around different pipes and tubes.

You can easily do that on your own, but if you don’t, make sure your mechanic inspects the engine every time you get an oil change. Take car of any oil leaks as soon as you detect them!

Give your diesel engine a minute before you turn in it off

This last tip is a hot topic among diesel car owners. Many believe it’s a myth, but trust is, it’s not.

If you shut down a diesel engine immediately, the residual heat in the engine can cause heat soak. Heat soak occurs when the heat from the engine isn’t dissipated because there is no coolant flowing. This can cause the temperature in the engine compartment to rise, which can damage various engine components such as the turbocharger, pistons and valves.

If you let the engine idle for a few minutes before turning it off, this can also help cool down the turbocharger, which can get extremely hot during operation. Allowing the turbocharger to cool before shutting down the engine can help it last longer and prevent damage.

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