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Can You Use Synthetic Oil in a Diesel Engine? (Explained)

Choosing oil for your diesel engine vehicle is much more complex than it sounds. Especially when the popularity of synthetic oil is celebrated everywhere but you can’t decide whether it can be used in a diesel engine.

Here we’d like you to learn more about synthetic oil and know if you can use it in a diesel engine.

Can you use synthetic oil in a diesel engine?

You can use synthetic oil in a diesel engine. In fact, it’s the best choice as it ensures the engines’ long life and good protection. Synthetic oil has higher quality additives and thus offers better performance in a diesel engine. Also, it protects the vehicle from oxidation, breakdown, and more.

People who have a diesel engine in their vehicles hesitate when choosing between conventional oil and regular synthetic oil.

Since synthetic oil has gained much popularity for the benefits it offers, it’s obvious many wants to use it in the diesel engine. And they can certainly!

Synthetic oil offers several benefits for a diesel engine vehicle. It not only increases the lifespan but also provides protection from breakdown, wear and tear, and other issues.

Now let’s know if you can use these synthetic oils for a diesel engine:

Full synthetic for diesel engine:

Full synthetic oil is made of synthetic base and additives. It’s more powerful to boost the performance of a diesel engine.

Full synthetic oil fights against slugging, deposit buildup, technical breakdowns, etc. more efficiently. So it can be used in a diesel engine without any doubt.

Semi-synthetic for diesel engine:

Semi-synthetic oil is a mixture of conventional oil and regular synthetic oil.

Although they are not much efficient as full synthetic ones, they provide better service than regular motor oil. For a diesel engine, it can be used as a cheaper yet mid-level oil.

Is synthetic oil better for diesel engines?

Synthetic oil undoubtedly is full of benefits. Not only does it protect your vehicles’ parts from wearing off also lasts more than usual oils. Besides, when used in vehicles’ this oil offers cleanliness, efficiency, and smoothness.

But is synthetic oil better for diesel engines too? We’d say a capital YES!

Better protection:

People who use synthetic oil in their diesel can have their engine and motor parts protected from wear and tear.

Besides, synthetic oil is much more powerful to stand against common issues of a diesel engine such as oxidation, discoloration, or breakdown.


synthetic oil when used in a diesel engine, goes longer. It’s more stable than conventional oil and has a lower tendency to convert. Thus you don’t need to change the oil frequently like other oils.


If you use synthetic oil in a diesel engine, you will not have to input a large amount. Compared to conventional oil, you might need half of the synthetic oil to cover a similar travel distance.

So even if it seems synthetic oil is more expensive than conventional oil, it saves much money.

Longer oil change intervals:

Synthetic oil doesn’t need to be changed as frequently as conventional oil. It can last a minimum of 8000 miles to 25000 miles or even more with a long oil change interval.

Thus you get to save some bucks, much time, and still enjoy a smooth ride experience.

What is the disadvantage of synthetic oil?

Synthetic oil is one of the best oils to use in diesel engines. It is much more protective to the vehicles’ engine and motor parts comparing any other oi.

But before you decide to go for synthetic oil, we’d like to inform you about some of the advantages of this oil. So that you get to know both sides before selecting.

Higher cost than conventional oil:

synthetic oil costs more than two or four times more than regular conventional oil.

The manufacturing price of this oil is the main reason it’s more expensive than petroleum-based oils. Also, changing the oil after a certain time leads to more cost.

Not suitable for every engine:

even if you somehow cope with the cost, you may not be able to use synthetic oil on every type of engine. Synthetic oil isn’t suitable to use in rotary engines as it can get sticky when burnt.

Limits the breaking in:

Synthetic oil doesn’t let new vehicles run expertly as its friction resistance limits the breaking in.

It reduces the friction in newer engines so the operating parts might get almost zero friction thus the vehicle can’t run properly.

What kind of oil do you use in a diesel engine?

While pampering your vehicle that has a diesel engine, you want to choose the best of everything. For example, the oil.

Depending on what type of oil you’re using in your diesel engine, the game of running the vehicle can change. So you must research well before choosing oil for a diesel engine.

Diesel engines have a thicker and heavier form and work with much force. Oil in a diesel engine gets consumed at an elevated rate of compression ratio. So it’s better to go for 15W-40 while selecting oil for a diesel engine.

15W-40 has many benefits on a diesel engine vehicle, such as tractors, lights trucks, cars, etc. Using this type of heavy-duty oil ensures a smooth and efficient journey.

How many miles can a diesel go on synthetic oil?

You can cover around 7500 t0 10000 miles using synthetic oil on a diesel engine that’s a duration of 6 months to 1 year on average.

But this may change due to the vehicle’s condition and the brand of the oil. Moreover, depending on whether it’s a full or semi-synthetic oil can change the distance.

You’ve already known that synthetic oil lasts longer than conventional oil.  It’s because of its’ slow consumption that leads to less oil change frequency.

Moreover, its ability to reduce friction and boost engines’ capacity has an impact on the distance a diesel can go on synthetic oil.

Without changing the oil in between, a diesel can run for 7000 to 7500 miles at least. But if the duration of use increases the distance may change.

How often to change synthetic oil in a diesel engine?

Usually, diesel engines need more oil changes but if you use synthetic oil in a diesel engine, it requires less oil change than conventional oil.

It’s suggested to change the oil every six months that’s equal to approximately 5000 to 7000 miles of running. But it’s applicable if the vehicle is involved in average towing. Otherwise, the oil can be changed after a year too.

The oil change in a diesel engine also relies on the land or ground and the climate as well. Also what type of synthetic oil you’re using, full or semi-synthetic can affect the timing of oil change in a diesel engine.

If a vehicle performs heavy towing and runs at a higher speed, it will need to change the oil every 3 months, which is 3000 to 5000 miles on average. 

However, you should never drive for more than 1 year without changing the oil despite any condition.

Can synthetic oil be mixed with conventional oil?

It may happen that you are suddenly running short on synthetic oil so you have no way than using conventional oil in your diesel engine.

So you might think that mixing synthetic oil with conventional oil will bring you trouble. Fortunately, you can mix these two types of oil without worrying.

Conventional oil and synthetic oil both are made from base oils and additives. In conventional oil, the base oils are usually filtered from crude oils such as gasoline, heating oil, etc.

On the opposite, synthetic oils base, oil is chemically produced. Both are the same except synthetic oil has components of higher quality.

So you can mix synthetic and conventional oil. But you will see no great improvement. Instead, you may experience poorer performance sometimes so it’s better to not mix these two oils except emergency.

Can I switch back to regular oil from synthetic in diesel engine?

You can always switch back to regular oil from synthetic oil in a diesel engine. It will not harm your engine and the idea is supported by manufacturers too.

Getting impressed by its advantages many people start using synthetic oil in the diesel engine. No doubt, it brings the best facilities but the cost might not always be carried. Also in newer cars, people don’t feel the urge to continue using this expensive oil.

So many users want to switch back to regular oil and that’s very possible. Synthetic and conventional both are the same only the synthetic has higher quality components.

Final Thoughts

Synthetic oil is better than regular oil as it provides great performance and smoothness. It protects against engine breakdown, slugging, buildup, and motor parts’ wear. It expanded a vehicles’ life duration too. So considering all these synthetic oils can be used in a diesel engine.