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Top 6 Best Synthetic Oil for Diesel Engines

Maintaining a peak-performing diesel engine is an essential part of owning a diesel vehicle. The best way to keep the gears running is by using only the best synthetic oil for diesel engines. But how do you know which synthetic oil is best for your diesel engine?
To help you with that, we’ve listed the best brands and compared them. We’ve also picked out some of their most amazing products. Our judgment is based on grading, certification, ODI, and engine compatibility.
So without any further ado, let’s get started!

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best synthetic oil for diesel engines

Mobil 1 Super 96819 15W-40 Delvac
  • Extends the life of the engine.
  • Reduces sludge and deposits.
  • Long life of seals and gaskets.
Castrol EDGE 5W-30 C3 Advanced Full Synthetic Motor Oil
  • Reduces friction.
  • Conserves engine power.
  • Prevents abrasion and corrosion.
Valvoline Premium Blue Extreme SAE 5W-40 Full Synthetic Engine Oil
  • Works in extreme conditions.
  • Protects the engine from oxidation.
  • Enhances fuel efficiency.
Royal Purple 15W 40
  • Protects from corrosion.
  • Superior wear protection.
  • Extends oil change intervals.
Shell Rotella T4 15W 40
  • Promotes longer engine life.
  • More efficient engine function.
  • Reduces emissions from the exhaust.
Castrol EDGE 03087 5W-30
  • Requires lesser frequent draining.
  • Prevents wear six times faster.
  • Better fuel economy.

Overall #1 Rated Pick

Mobil 1 Super 96819 15W-40 Delvac

Mobil 1 Super 96819 15W-40 Delvac

We chose the Mobil 1 Delvac Super 1300 as our top pick. The reason for this is that it compares so well to the other products in the market. It features an extended oil drain interval that goes 1.5 times beyond the regular OEM recommendation. Plus, it’s known to exceed most, if not all, API requirements. This includes API CK-4, CI-4 PLUS, CH-4, and many more.
The Super 1300 is always ready to go over the top. It’s the perfect choice for heavy-duty engines such as threshers, harvesters, tractors, trucks, and ships. It’s also one of the best when it comes to driving both on and off the highway. If you’re someone who owns a truck or some sort of heavy vehicle, then this is the best diesel oil for you. If you own a fleet of excavators, cranes, and construction vehicles, then the Super 1300 is also the best deal for you.

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Synthetic Diesel Oil Comparison

Want to know what the best synthetic oils are for diesel trucks and wagons? The best way to do so is to look into what others have to say. A quick review of the marketplace reveals that most suggest big brands such as Mobil 1 and Castrol. But many times, it’s not about the brand, but actually the mileage of your car.
If your car has lower mileage, a lighter-grade full synthetic oil for diesel engines will work. It includes anything from 5W-20 to 5W-30. Lighter oils require less frequent oil changes, and are great at keeping your engine in top shape.
If your car has higher mileage, you’ll need heavier grade oil. For example, on a Honda Accord, 5W-30 synthetic diesel oil does the trick. You can also opt for the 5W-40 synthetic diesel oil if your vehicle is a bit older. Both of these will help to preserve the engine’s life and keep the car running smoothly. 10W-30 oil seems to work great too.
However, many people are of the view that you should just stick to the manual. Frequently, the car/truck has a brand of oil that it’s best compatible with it.


Brand SAE Summary
Mobil 1 15W-40 Best for extreme conditions
Castrol 5W-30 Best prevents oil breakdown
Shell Rotella 15W-40 Best for high compatibility
Valvoline 5W-30 Best for product and grade versatility

Best Synthetic Oil for Diesel Engines

Mobil 1 Super 96819 15W-40 Delvac

Mobil 1 Super 96819 15W-40 Delvac
No name has hit the diesel oil market with more fervor than Mobil 1. What sets the Mobil 1 Super 1300 aside is that it’s made to work under all conditions. With its low-temperature pump ability and fluidity, you get a smooth silk startup even in the winters. To add to that, the Super 1300 fully synthetic diesel engine oil meets API CJ-4 and CK-4 requirements! To put that in perspective, diesel oil has a long after-treatment life, and can handle mixed fleet operations. Recommendation: It is the best Mobil 1 15w40 fully synthetic diesel oil, made for fleets of trucks, wagons, and fleets.
Technical Specifications:
  • Meets API CK-4 specifications.
  • Soot and viscosity control.
  • Excellent TBN reserves.
  • Fluid even at low temperatures.
  • Compatible with most car parts.
Extends the life of the engine.
Reduces sludge and deposits.
Long life of seals and gaskets.
Higher engine efficiency.
Reduces oil costs.
May cause potential injector failures.

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Castrol EDGE 5W-30 C3 Advanced Full Synthetic Motor Oil

Castrol EDGE 5W-30 C3 Advanced Full Synthetic Motor Oil
The Castrol Edge C3 brings out the best in your engine. It strengthens the oil fill by up to 30%, and helps to reduce friction and conserve power. The SAE of this model is 5W-30 and is thrice as strong as other benchmarks in preventing viscosity breakdown. Along with that, the Castrol Edge C3 meets API SN PLUS, ILSAC GF-5, and multiple OEM specifications. It’s made for engines that operate at a higher temperature. Recommendations: We recommend the Castrol Edge C3 as the best 5w30 synthetic diesel oil for high-temperature applications.
Technical Specifications:
  • Strengthens oil film by 30%.
  • Fights wear six times better.
  • Meets OEM specifications.
  • Uses Fluid Titanium.
  • Minimal friction for better performance.
Reduces friction.
Conserves engine power.
Prevents abrasion and corrosion.
Made for BMW, Mercedes, and VW.
Highly qualitative.
Low availability in physical stores.

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Valvoline Premium Blue Extreme SAE 5W-40 Full Synthetic Engine Oil

Valvoline Premium Blue Extreme SAE 5W-40 Full Synthetic Engine Oil
It is one of the best synthetic oil for Ford 6.7 diesel engines by Valvoline. It uses a superior synthetic stock that allows you to start up your car even during cold, clammy winters. Along with that, you get the benefit of oil oxidation protection and enhanced thermal protection. Using the Valvoline will prove to be a good choice. It meets standards set by Cummins, Detroit Diesel, Mack, Volvo, and even Caterpillar. Recommendation: It is the best Valvoline synthetic diesel oil if you have a large fleet of diesel trucks.
Technical Specifications:
  • Safer starts in freezing weather.
  • Meets many requirements.
  • Better fuel economy.
  • Protects against oil oxidation.
  • For both on and off-road.
Works in extreme conditions.
Protects the engine from oxidation.
Enhances fuel efficiency.
Prevents knocking.
Versatile applications.
May leak during transit.

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Royal Purple 15W 40

Royal Purple 15W 40
The Royal Purple Duralec Super is a great way to kick-start an oil change on your diesel engine. This bottle of oil goes beyond specifications laid down by Dexos 1 and ILSAC GF-5. It is also licensed by API, which only adds to its already abundant feature set. Duralec Super from Royal Purple can handle both high and low temperatures. It is recommended to allow the engine to “break-in” (run about 8,000 miles) before using this oil. Recommendations: We recommend the Duralec Super as the best Royal Purple 15w40 synthetic motor oil for commercial use.
Technical Specifications:
  • Goes beyond Dexos1 specs.
  • Patented ZDDP additives.
  • Removes existing sludge and deposits.
  • API-licensed diesel oil.
  • Increases efficiency of fuel consumption.
Protects from corrosion.
Superior wear protection.
Extends oil change intervals.
Licensed by the API CK-4.
Greatly reduces exhaust emissions.
Quart sizing may be inaccurate.

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Shell Rotella T4 15W 40

Shell Rotella T4 15W 40
As diesel engine oil, the Shell Rotella stands above the rest. It is due to the high level of protection it offers to the engine. For instance, this oil protects your engine from oil oxidation 50% longer as compared to similar brands. And it can keep the system 50% more corrosion-free and wear-free than most benchmarks. It is great diesel oil for its heightened oil aeration, enhanced viscosity, oil pressure control, and much more. Plus, it’s been tested and approved with an API CK-4 certification. For this reason, it’s one of the best synthetic oil for diesel tractors. Recommendation: The Shell Rotella T4 Triple Protection is the best Rotella 15w40 full synthetic oil for protecting your engine.
Technical Specifications:
  • 50% longer oxidation protection.
  • API-CK-4 licensed.
  • Prevents 50% more wear.
  • More durable emission control system.
  • Better oil aeration.
Promotes longer engine life.
More efficient engine function.
Reduces emissions from the exhaust.
Prevents engine knocking.
Prevents oil breakdown.
Seals may break on impact.
Gallon bottles are prone to leaking.

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Castrol EDGE 03087 5W-30

Castrol EDGE 03087 5W-30
Here’s Castrol motor oil, this one made for handling the tougher jobs. The Castrol EDGE Extended Performance has a 20,000-mile drain interval. It’s made with Fluid Titanium technology that provides high resilience even under heavy pressure. This Castrol oil is best for heavy-duty jobs such as towing, hauling, and idling. It’s made to work in dusty, cold, humid, and even hot environments. Recommendations: We recommend this as the best Castrol synthetic diesel oil for carrying out heavier operations.
Technical Specifications:
  • 20,000 miles drain interval.
  • Best for towing and hauling.
  • Fluid Titanium technology.
  • Reduced engine deposits.
  • Works in extreme temperatures.
Requires lesser frequent draining.
Prevents wear six times faster.
Better fuel economy.
Can handle all types of weather.
Perfect for hauling and towing.
Gets dirtier faster.

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Synthetic Oil for Diesel Engines Brands

Here are the top brands for the best synthetic diesel engine oils:

Castrol Synthetic Diesel Oil

Castrol is one of the world’s top leading brands that manufactures and sells lubricants. Based in the UK, this 120-year-old company operates in over 40 different countries. It produces lubricants solely made for motorbikes, two and four-stroke engines, and diesel engines. All of their products, especially the gas and diesel oils, keep your engine in top shape. They prevent knocking, burning, depositing, and control exhaust fumes.
If you’re looking into buying Castrol diesel oil, we recommend the Castrol EDGE Extended Performance. This oil is made for use in tractors, tow trucks, and heavy agricultural equipment. It’s excellent for home use as well, if you own a semi-truck or a wagon.

Valvoline Synthetic Diesel Oil

Valvoline Inc. is a worldwide manufacturer, supplier, and marketer of premium quality lubricants and oils. Having a rich history of over 150 years, the brand has been ranked as the No. Three motor oil brands for passenger cars. And their diesel engine oils are no different.
The brand also prides itself on providing quick car services, operating over 14,000 such centers. The Valvoline trademark brand name is an industry-standard diesel engine oil manufacturer.
One of their best assets is the Premium Blue Extreme oil for diesel engines. Available in multiple grading, the oil is essential for your truck or trailer. Due to its cheap cost, it’s also preferred for larger fleets and dispatchers, especially online stores.

Royal Purple Synthetic Diesel Oil

Another name that shines out from the rest is Royal Purple. Situated in Porter, Texas, Royal Purple provides the widest range of products for cars and trucks. This company has had over two centuries of experience, making formulae for engine lubricants. While other companies strive to compete in the synthetic world, Royal Purple trumps even the natural variants.
For anyone who wants to try it, we’d recommend the Royal Purple Duralec Super. It’s one of the best diesel engine oils if you want to maximize your engine’s performance. It works in all conditions- wet, dry, cold, humid, and at extreme temperatures.

Mobil 1 Synthetic Diesel Oil

Last but not least, we have the Mobil 1 synthetic diesel oil. This is, by far, the most commonly heard-of brand. But the performance isn’t just hearsay– Mobil 1 certainly outperforms some of the biggest contenders. With over 46 years of experience, Mobil 1 stands at the top of the oil industry.
This brand produces lubricants for cars, trucks, motorbikes, tractors, and even heavy machinery. Their product range is versatile and extant. Each series of diesel oils is designed with your engine’s performance in mind.
If you want to try it out, then why not try your luck with the Mobil 1 Delvac Super 1300? It’s a good product, given the low price range. It’s best to prevent knocking, burning, and controlling exhaust fumes. And it works even in the winters, providing a lightning-fast ignition.

Synthetic Oil for Diesel Engines – Buyer’s Guide

Knowing what should go into your delicate diesel engine is no less than an art. You need to do a lot of research, search through forums, and refer to various websites. To save you from all that hassle, here are a few tips that will help you make the right decision.

Oil viscosity

Oil viscosity is a measure of how easily you can pour the oil at a specific temperature. It’s usually represented in the format XW-XX. The ‘W’ stands for winter, and the X before that the viscosity of the oil at 0 degrees Celsius. The next two X’s represent the viscosity at 100 degrees Celsius. All of this will tell you thick or thin the oil becomes in certain weather.

As a general rule, the higher the W rating, the less compatible oil is in the winters. Also, if the high-temperature viscosity is higher, that means the oil will thin less.
For instance, 0W-30 grade oil will thicken less in the cold and thin faster in the heat. A 15W-50 grade oil, however, won’t work well in either weather. This highly depends on the engine and car model you have, so always be sure to do research on that.

Oil Drain Interval

This refers to how often you need to change the motor oil while driving. It’s usually measured in the number of miles you should run before changing it. Many owners believe you should change the oil every 5,000 miles. But the interval is given on most diesel engine oil boxes.
A longer interval will save you the pain of changing the oil every so often, which is especially annoying if you’re always making short trips, or own an extensive fleet of heavy vehicles.

Changing Oil

Changing the oil in your diesel engine is pretty simple if done right. You’ll be needing the oil, oil filter, drain pan, a wrench, a funnel, some gloves, and an empty container. Drain your water separator, turn off the engine, and remove the dipstick.

Raise and secure your vehicle and remove the drain bolt. Let it drain completely, replace the bolt, and then remove the oil filter. Replace with the new filter.
Now open the fill cap and use the funnel to pour in the new oil. Start your own and reset the oil lamp and wait for a few minutes. Now your vehicle is ready to run!

If all that is too wordy, then you can always have a look at this video below:


Finally, check for certification and factory specifications. Particularly, look for an API license, preferably the API CK-4 or CJ-4. A few other standards exist, such as OEM and Cummins, along with Caterpillar and ILSAC GF-5. These standards can mean a lot in terms of oil stability and engine life. So always choose your product very wisely.