Best Diesel Oil For Your Car

09th Sep,2023

“What oil do I need for my car?” This is probably a question you’ve been asking, and it has led you to the right place. Like any other buying decision for our car, we can’t simply pick any oil if we want to get that maximum performance. In this case, we’ll be discussing diesel oil. We have a separate article for the best 0w-20 synthetic oils.

We’ve outlined the outstanding products in the market so you’d get to decide the best diesel oil for your vehicle. Each oil has a quick but detailed review plus pros and cons to help you make the right decision. Without further ado, here are the best diesel oils in the market today.

Top 5 Diesel Oil – Reviews & Buying Guide

1 – Royal Purple 15w-40

First on our list is a full synthetic oil from Royal Purple. Armed with an API license, dexos1 certification, and ILSAC GF05 certification, the Royal Purple 15w-40 is easily one of the best. It works to improve your engine’s life and protect it from grime buildup. If you’re looking for a diesel oil for heavy-duty vehicles or older models, then this one from Royal Purple is perfect.

Versatility is the strongest suit of this diesel oil, primarily because it works on both diesel and gasoline engines. It can also be used with conventional or synthetic oil, even the ones containing ethanol. The Royal Purple 15w-40 is formulated with premium base oils so you can get the best possible performance from your car.

From many independent tests, this motor oil has proven that its high-strength film is indeed 2-3 times stronger than other synthetic blend oils. And with Royal Purple’s proprietary additive technology, metal-to-metal contact is prevented and the emission catalyst system is prolonged. 

As such, you’re sure that your engine is well-protected from wear and corrosion.

  • Works with gasoline and diesel fuel engines
  • High-strength film protects against corrosion
  • No engine leaks
  • Increases fuel efficiency
  • API licensed

  • Customers say that the amount of fluid inside the container is a bit less than the declared volume

Cleaning is another thing that this diesel oil does best. It effectively flushes away all the sludge and various deposits left by previous oils. Eliminating all that dirt and debris is extremely important in sustaining your engine. This way, moving parts are guaranteed clean and performance becomes more efficient. 

You don’t have to worry about increasing your gas costs, too. The Royal Purple 15w-40 is proven to increase fuel efficiency, thus saving you money as well.

Overall, the Royal Purple 15w-40 provides great cleaning capabilities and superior protection for your engine. It can be said that picking the right diesel oil is part of maintenance, and you won’t go wrong with this choice. 

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2 – Shell Rotella T6 Synthetic Diesel Motor Oil 5w-40 CJ-4

Shell is probably one of the brands topping the list when you type in “what oil for my car” in a search engine. Some of the best engine oils in the market are produced by Shell. One of their most prominent oils is the Rotella T6, a full synthetic oil, meaning it has no crude oil in the formula. 

This heavy-duty synthetic blend effectively cleans your engine and protects it from harmful contaminants. Infused with multi-functional dispersant additives, the T6  expertly eliminates all the dirt and gunk so your engine is kept running smoothly. With all the debris gone, you’ll really see the difference because your vehicle will pack in more power when doing heavy tasks like hauling. The Rotella T6 motor oil also works for both gasoline and diesel-powered vehicles, so you don’t have to worry about compatibility issues and whatnot. 

If you’re looking to pass an upcoming emissions test, the Rotella T6 is definitely the diesel oil for the job. It has a low-ash formulation that aids in controlling exhaust levels and helps adapt to driving conditions.

  • Superior cleaning and protection
  • Improves fuel efficiency
  • Handles hot and cold temperatures well
  • Ensures a smooth, steady flow for optimum performance

  • Packaging may leak during shipping
  • Lubricating factor may diminish over time

When it comes to temperature handling, the T6 works remarkably well. Equipped with Shell’s Triple Protection Plus Technology, this diesel oil remains stable even in extremely hot or cold temperatures. This is great for cars that travel between places that have changing weather, or even if you just live somewhere with fluctuating temperatures. 

Fuel economy is another thing that customers look at when buying the best diesel oil. The T6 is guaranteed to deliver on this all-important feature by improving fuel efficiency by 1.5 percent. So when you regularly use this oil, you get more savings on fuel costs.

Are there any reasons to complain? Well, customers have reported leakages when the package was delivered to them. There are also those who say that the lubricating factor of the oil lessened over time. Despite these minor issues, the Shell Rotella T6 remains a great choice if you want great performance for a lower price. 

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3 – Castrol Edge Extended Performance 5w-30

Castrol is another one of the well-known brands in the automotive oil industry. This particular turbo diesel engine oil is the best choice for the demanding engine. That’s because it is capable of handling extreme pressure from modern cars and vehicles. Where other diesel oils would break down, the Castrol Edge Extended Performance 5w-30 can handle both low and high heat pressures with ease. 

Its titanium fluid strength is one of the standout features of this motor oil. This restricts the diesel oil from breaking down even in lower viscosity. Through this liquid engineering, metal-to-metal contact is lessened by 45 percent and friction is reduced by 15 percent. Furthermore, the ultra-strong film enabled the oil to last more than 140 hours longer than the Castrol oils formulated without titanium. 

  • Titanium-strength fluid
  • Great for modern high-performance engines
  • Handles extreme pressure well
  • Effective cleaning capabilities to ensure peak performance

  • Some customer would’ve liked longer use between changes

The Castrol Edge Extended Performance 5w-30 works amazingly well with high-performing vehicles. It clears away all the grime and debris to ensure a smooth flow of oil through your engine’s moving parts. More importantly, it provides maximum protection from corrosion and wear, effectively extending the life of your engine. 

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4 – Mobil 1 Synthetic Motor Oil 0w-40

If you’re looking for something with a low viscosity grade, the Mobil 1 Synthetic Motor Oil 0w-40 is one of the best diesel oils you can buy. As the name tells us, this diesel oil has a 0w rating, meaning you’d have no problems driving to colder regions. It can handle temperatures as low as -40° F, enabling it to withstand the freezing cold. But it’s not just low temperatures that can be handled by this diesel oil. It also works well even in temperatures as high as 500° F. In short, this particular diesel oil is an excellent pick if you’re going to be needing protection for extreme weather conditions. And obviously, you do need your vehicle to be as reliable as possible when faced with an intense climate. 

In terms of engine-cleaning action, the Mobil 1 Synthetic Motor Oil 0w-40 is a superstar. Dirt, soot, and debris that build up will be immediately be removed so your vehicle can perform at full power. When an engine is clean, we improve its fuel efficiency and lengthen its life. Aside from that, it will also take longer between oil changes so you can get the most out of your diesel oil.

  • Tolerates cold and hot temperatures easily
  • Withstands extreme weather
  • Cleans and lubricates well
  • Great protection from wear and tear
  • Improve engine performance

  • It’s a hassle to measure because it comes in quarts
  • Some customers say that the packaging has leaks when they received it

It’s also important to note that this diesel oil can be used with gasoline or diesel engines. So whichever one you have, you get great protection and lubrication so your engine can operate at optimum levels and you can have peace of mind on the road. Overall, the Mobil 1 Synthetic Motor Oil 0w-40 gives you a smooth run without worries about pressure and temperature handling.

A minor issue that customers complain about in this diesel oil is that it comes in quarts. Motor oils typically come in gallons but this one does not. Because of that, you need to pay extra attention when getting measurements so you’ll get it right. 

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5 – Motul 007250 8100 X-cess

To wrap up this review list, we’re finishing off with the best diesel oil for the latest and most powerful cars — the Motul 007250 8100 X-cess. This product is a multi-purpose oil approved by car manufacturers as one of the best for turbo diesel, high-powered engines, catalytic converters, and gasoline direct injection.

Your engine will definitely be performing at its best because this diesel oil is fully synthetic, meaning no crude oil was used. Among the many benefits of synthetic oil include resistance to oxidation, better temperature handling, improved fuel economy, increased horsepower, protection against deposits, and generally a longer engine life.

Formulated with choice base oils, the Motul 8100 X-cess diesel oil handles extreme temperatures very well. A common problem with other oils is that they start to break down during the cold weather. Some drivers get frustrated because their engine won’t immediately start during the winter. Fortunately, the Motul 8100 X-cess provides better lubrication if you live somewhere with extreme weather. Whether it’s freezing cold or scorching hot, you can always depend on this diesel oil to make your engine as reliable as possible.

  • Excellent lubrication
  • Best diesel oil for the latest and most powerful cars
  • Reliable when handling cold or hot temperatures
  • Lengthens engine life
  • Compatible with gasoline and diesel engines

  • More expensive than others

When it comes to fuel efficiency, this diesel oil is tested and proven to decrease oil consumption. It has low viscosity and low volativity. As such, it takes less power from your engine, thus reducing the amount of fuel you usually use. Fewer trips to gasoline station is something that every driver wants, without sacrificing performance of course. Plus, it’s more environment-friendly too since you reduce oil waste. Additionally, the low viscosity grade of the Motul 8100 X-cess lowers exhaust emissions, so you’ll be fine with emission tests. With this diesel oil, your engine will become more responsive as well.

The Motul 007250 8100 X-cess also meets a wide range of standards, including API and ACEA. It also has a bunch of OEM approvals, so it’s convenient to use wherever in the world. Versatility is a strong point in this diesel oil as it can be used whether you’re using a gasoline or diesel engine. 

Overall, the Motul 007250 8100 X-cess is definitely one of the best in the diesel oil market. It provides great lubrication, resistance to wear, and long life for your engine parts. The only catch is that it’s more expensive compared to others out there, but  you essentially get what you pay for with this diesel oil.

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Our Top Pick – Royal Purple 15w-40

The top spot lands on one of the most versatile engine oils, the Royal Purple 15w-40. Whether you have a gasoline or diesel engine and use either conventional or synthetic oil, this diesel oil from Royal Purple has you covered. Its superior cleaning capabilities gets rid of soot, dirt, grime, debris, and all the other unwanted gunk that wear your vehicle out. Formulated with an extra-strength film, it provides a thick lubrication to prevent metal-to-metal contact so your engine parts are always performing at peak level. And with an API license, you’re guaranteed to be satisfied with the performance and capabilities of this diesel oil. Clean, fuel-efficient, and well-maintained — these are all the things you can expect from the Royal Purple 15w-40.

How to Choose the Best Diesel Oil

With the mountain of brands and products to choose from, choosing only the best oil for your vehicle may be overwhelming. The variety of viscosities, certifications, additives, and other information may easily confuse drivers, especially beginners. Since selecting the oil will contribute to the maintenance of your vehicle, taking the time to make a choice will definitely pay off. Filters are another matter, and there are great choices for synthetic oil filters. Here, we discuss the factors you should consider when buying oil so you can make a wise decision.

Look at the manual

Before heading off to the store, you should get to know what your vehicle needs first. Your car manual will tell you the manufacturer’s recommendation for the oil weight, so you know this info before you make a purchase.


Viscosity basically tells you how resistant the oil is to flow. You’ll see something like “10w-30” or “5w-40”. This is a crucial factor when choosing the best oil because you get to know how the oil will work under extreme temperatures. The first number represents how resistant the oil is in cold weather, as the w stands for “winter”. Generally, the closer the number is to zero, the better it will perform in the cold. On the other hand, the second number represents how resistant the oil is to thinning in hot weather. The higher this number is, the better. Nevertheless, you should still follow the manufacturer’s recommendations as stated in the manual.


Not all oils are compatible with both gasoline and diesel engines. Thus, you should always check first before buying a diesel oil.


Combustion produces a lot of grime and varnish deposits, which, when not cleaned, will cause damage to the engine. Having additives is one way of improving the cleaning process so that the engine will be protected from rust, corrosion and wear. Diesel oils have different kinds of additives, with some brands incorporating their own technology to reduce friction, inhibit corrosion, and improve overall engine performance.


Diesel oils come in a variety of prices from cheap to expensive. It’s important to be wary because sometimes some sellers ask for a higher price than what the manufacturers are advertising. The same way, some stores may sell at a lower price. Having said that, you should still review what the diesel oil offers because an expensive price tag doesn’t necessarily equate to a better product. 


Diesel oil is produced by numerous brands in the market, but not all of them are made equal. Viscosity grade and additives are just two things that differ between diesel oils, and there are a few other factors that set some apart from the competition. Whatever the case, the best oils should be able to provide protection from engine wear while boosting performance. Diesel oil is typically cost-effective, but it should be effective also in cleaning and handling engine pressure.

We hope these reviews of the top diesel oils helped you in deciding what to buy for your vehicle! There are tons of other helpful buying guides as well, including this comparison of belt drive and chain drive as your effective garage door openers.

Be more of an educated driver—learn more about the things you should consider in buying a car!

William Johnson

William Johnson is the owner and founder of He writes about car accessories, with his passion stemming from a deep enthusiasm for all things automotive. His website, RRD, focuses on in-depth reviews of car accessories to help people find the best and latest products in the market.