There are a plethora of different engine oils out there, so you might be wondering what makes diesel engine oils unique. The main thing that differentiates diesel engines from petrol is the lack of spark plugs. To get combustion, diesels simply use compression to generate it instead.
The best diesel engine oils generally have a lower temperature flow and higher viscosity. There are oils out nowadays that even work in both petrol and diesel engines. And with the level of oil additives and modern synthetic tech now available in motor oils, the choice is wider than ever.
With that said, however, diesel-only oils have higher anti-wear properties than petrol oils. If mistaken for one another, you could damage the engine due to overheating caused by wear. But most 10W-40 oils nowadays are compatible with both petrol and diesel engines to make life easier.
The best diesel engine oils at a glance:
Editor’s pick: TotalEnergies Quartz 7000 10W-40, 5L – Buy from Amazon.
Best comprehensive diesel engine oil: Castrol Magnatec 5W-40 DPF Engine Oil, 5L – Buy from Amazon.
Best 10W-40 diesel oil: Mobil Super 2000 X1 10W-40, 5L – Buy from Amazon.
If you are changing your engine oil, consider changing your oil filter at the same time, and because choosing the right oil can be confusing, we’ve created a shortlist of the best diesel engine oils out there. We’ve chosen the best that suit each engine-related needs, from 5W-30 oils and more, and explain how you can find the right oil for your vehicle.
How to find the correct diesel engine oil for your vehicle
Find the correct parts for your car
Pros
- Easy to filter
- Huge variety of cars on the database
Cons
- You need Prime for free delivery
The best diesel engine oils
Editor's pick
It's designed to prevent sludge build-up in engines as they rack up the miles, and it ensures cleanliness and resistance to oxidisation (degradation/corrosion of parts) which helps prolong an engine's life.
Pros
- Very advanced
- Full synthetic means better engine protection
Cons
- 10W-40 won't suit all
Best comprehensive diesel engine oil
The Magnatec range also helps keep engine wear at bay from common causes such as warming up, stop-start procedures, and heavy cam load.
Pros
- Does a great job at protecting your engine
- Great at both high and low temperatures
Cons
- Full synthetics are more useful to higher-mileage vehicles
Best for high tech diesels
It's made using synthetics and optimises cleanliness and performance in turbodiesel engines with modern, clever tech. Liqui Moly even say it helps keep the diesel particulate filter (DPF) in good order.
Pros
- Maintains diesels and petrols in good order
- Healthy number of compatible cars
Cons
- 5W-30 isn't the one for everybody
Best 10W-40 diesel oil
It's semi-synthetic which means a load of extra additives have been mixed in to make your diesel engine breathe cleanly and run smoothly. Diesel engines are also widely used for a lot of motorway use, so it's useful to know that the Super 2000 is designed to withstand high temperatures at ease.
Pros
- Great at protecting your engine
- Semi-synthetic means good additives
Cons
- Some diesels will suit 5W-30 better
Best fully synthetic diesel engine oil
It is more car-specific than other oils, though. It's compatible for BMW Group petrol and diesel engines amongst some others, but if you're considering this bottle, do a double-check to make sure it suits your car's engine.
Pros
- Fully synthetic means extra protection
- Perfect for daily use of cars
Cons
- Not suitable for all models
What to remember about diesel engine oils
You will have noticed that we’ve included engine oils that are compatible for both petrol and diesel applications. While diesel-only oils are out there, they tend to not be as good as the combined products from the big brands. And when you consider that modern engine oils are largely made up of synthetics, it’s only brought the compatibility of the two fuel types closer.
Nevertheless, diesels are generally happy with 5W-30, 5W-40, or 10W-40 oils or higher viscosities. Ideally, a good diesel engine oil has to run smoothly on cold starts as well as warm/hot cruises. They should treat the DPF filters and turbochargers with good health since these can get clogged overtime. But you should always check if your car can take the oil before purchasing. Otherwise you could run into issues, such as overheating or seals wearing out more quickly. Four-stroke engine oils for motorcycles simply won’t be fit for use in a car engine.
Lastly, while some oil manufacturers recommend longer intervals between changes, this doesn’t necessarily mean it fits into your lifestyle. High mileage engine oils tend to advertise this sort of thing. For example, if an oil recommends changes every 15,000 miles, it’s likely catered for individuals who can cover that many miles in a year. Cars still need to be serviced on a consistent schedule. So, if you cover 3,000 miles per year, don’t drive for five years between oil changes or ignore other important lube changes such asaxle and gearbox oils or radiator anti freeze top-ups.
Frequently asked questions:
What brand of engine oil is best?
There are so many brands delivering quality oil that it’s impossible to answer. One brand may be perfect for one user but another may find it a bit less suitable. It’s really about choosing what is best for your situation.
Is 5w40 good for diesel engines?
This is a fairly common type of oil that can be used in both diesel and petrol engines with no real problems
What is the best oil for breaking in a diesel engine?
It’s usually best to stick to the manufacturer’s recommendations for this
What happens if I use 5w40 instead of 5w30?
A 5w40 oil will be very slightly thicker at normal engine running temperatures, so it will provide good protection, but it may cause a slight decrease in fuel economy
Is there a difference in oil for diesel engines?
The main difference is that diesel engine oil is likely to contain more additives to help it cope with greater engine pressure and assist with clean running.
What is the best oil for a high-mileage diesel engine?
Anything from 10W-40 oil and onwards will generally suit higher mileage engines as these are thicker and can sustain higher engine temperatures, but it’s always advisable to check the manufacturer’s specifications
Aaron Hussain is a commercial content writer at Bauer Media writing for Parkers and CAR. He is obsessed with classic cars and anything with a fascinating story to tell.
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