One of the most basic car maintenance, yet also one of the most important, is changing your oil. And yes, diesel engines need oil changes as well. But what exactly is the best synthetic oil for diesel engines? Well, that’s what we’re going to find out in this post. We’ll discuss the advantages of each one, which one you should get, and the benefits you may get by using synthetic oil.
Best Synthetic Oil For Diesel Engines: Why Do I Need An Oil Change?
Whether you have a diesel or a gasoline engine, it’s important to change your oil. The oil in your car’s engine acts as a lubricant for many of the moving components inside. Some of these components include the pistons, crankshaft, camshaft, timing chain, and many more. It lubricates these components so that it can reduce the amount of friction these parts experience.
By reducing the amount of friction, these parts can last longer and avoid major damage. Additionally, reducing friction also helps to reduce the amount of heat that these parts create. This means they’re less likely to overheat, and by remaining at their optimal operating temperature, they will last longer as well.
This is why neglecting to change your oil can sometimes lead to an overheating engine. Although it mostly comes down to your car’s cooling system, the engine oil can affect the engine’s temperature as well.
After a while, the oil in your car’s engine will break down due to age and the heat it experiences. It may also become contaminated with air, water, debris due to engine parts wearing down, and soot. As a result, the viscosity of the engine oil will change over time, usually, it becomes much thicker. When an oil thickens, it can’t lubricate the engine as efficiently.
Additionally, the engine will have to work harder since the thick oil makes it heavier for them to move. This is why an oil change is necessary, as oil have their lifespan. Neglecting routine engine oil change can result in very expensive damage, often requiring you to rebuild the engine which costs thousands of dollars.
When Should I Change My Oil?
Most modern cars require an engine oil change every 5,000 – 7,500 miles, or around every six months. However, some cars – especially older ones – usually require an oil change as early as 3,000 miles or every three months. Meanwhile, cars running on synthetic oil will usually require a change between every 7,500 – 12,500 miles. This is because synthetic oil use higher-quality base oil, which is more chemically stable and with higher protective quality, resulting in slower breakdowns of the oil.
However, these intervals will vary depending on your car’s make and model. We recommend checking your owner’s manual to find your manufacturer’s recommended oil change interval. Whatever they say in the manual, stick with it!
Best Synthetic Oil For Diesel Engines: Synthetic Oil Vs Conventional Oil
So, what exactly is the difference between synthetic oil and conventional oil? Should you use synthetic over conventional oil? Are there any other types of oil that you can use? Here are the types of engine oil available for your diesel engine:
Synthetic oil is artificially manufactured, consisting of synthetic base oils mixed with additives. This means they are more chemically stable, they’re often hydrophobic or water-resistant, and they can emulsify debris. All this means they break down much slower, hence the longer change interval for synthetic oils.
They can also result in a more efficient engine and fewer emissions. Additionally, since they’re less prone to breaking down, a sludge-prone engine will benefit from using synthetic oil. Sludge buildup is a gunky residue that from when the oil breaks down. Some engines are prone to this, such as VW’s 1.8L engine in the early 2000s. This is usually because of a design flaw, often caused by an undersized oil pan and difficulty dissipating heat.
However, synthetic oil has one downside: it’s expensive. They’re usually twice the price of conventional oil, sometimes maybe even four times the price. The longer change interval may offset the price difference, but your bank account will still feel that hit.
Conventional oil means the oil is made from mineral oil, so it’s a natural ingredient rather than synthetic. Diesel engine oil is usually made from crude oil, and this means it’s less molecularly stable compared to synthetic oil. Conventional oil can perform just as well as synthetic when they’re new, and you might not even notice it. But over time, they will break down much quicker, which is why they require more frequent changes.
This is because conventional oil doesn’t use additives. Resulting in an oil that’s more prone to contamination, and will change in viscosity much quicker. However, they’re quite a lot cheaper than synthetic oil.
Hybrid oil or sometimes called synthetic blend is a mix of conventional and synthetic oil. They’re usually still made from mineral oil, but they add additives so you get the advantages of full synthetic oil; longer lifespan, better performance, etc. However, because the impurities of crude oil are still there, it’s not as chemically stable and it won’t last as long as synthetic oil.
Hybrid oil is a good choice if you want the advantages of synthetic oil but at a lower price.
Should I Use Synthetic Oil Then?
If you don’t want to deal with oil changes often, and you don’t mind paying the higher price, then yes, go ahead. There are also some cases where you will benefit from using synthetic oil, such as:
- If you make a lot of short trips, you will benefit from synthetic oil. This is because the oil may not get warm enough during short trips, which means it won’t be able to burn off moisture and impurities in the oil. As a result, the oil will break down quicker. Meanwhile, synthetic oil is water-resistant and can emulsify debris on its own.
- Synthetic oil deals with extreme temperatures better. So, if you live somewhere with very cold winters or very hot summers, you’ll benefit from using synthetic oil.
- If you tow a lot or haul heavy materials, you will also benefit from using synthetic oil. It helps protect the engine from the strain that the extra weight puts on your engine.
- As mentioned, some engines are more prone to oil sludge. Certain engines from Volkswagen, Chrysler, and even Toyota are prone to this. Using synthetic oil will help reduce this engine oil sludge problem.
If the four things above don’t apply to you, and you’re on a budget, then there’s nothing wrong with conventional motor oil. There’s no need to go out of your way to use synthetic oil for your car. Just make sure you use the oil with the right oil grade for your engine. And of course, keep up with the regular oil change interval.
Top 5 Best Synthetic Oil For Diesel Engines
So now you’re probably thinking of buying synthetic oil for your diesel car. But which one should you get? Here are the 5 best synthetic oil for diesel engines:
1. Shell Rotella T6 Heavy Duty Diesel Synthetic Oil
The Shell Rotella T6 is probably the best and most popular synthetic oil for diesel engines. They claim that it can handle multiple kinds of driving conditions, and is good for both low and high-temperature protection. Shell also brands it as “heavy-duty diesel engine oil”, meaning it can be used for anything from small diesel hatchbacks to large utility trucks.
The price isn’t too bad either, 1 gallon or 128 fluid ounces of Shell Rotella T6 is about $36. While not the cheapest, it’s still cheaper than some other oil on this list and delivers good performance. Note, don’t confuse the Rotella T6 with the Rotella T5, the latter is a semi-synthetic oil.
2. Motul 8100 X-cess Synthetic Engine Oil
Motul claims that their 8100 synthetic engine oil is ideal for high displacement diesel and direct-injection gasoline engines. So, if you have another car with a gas engine, you can consider using this as well. They also claim it has great protection against soot and will offer better fuel consumption.
Reviews are generally positive, with positive feedback from many car owners including VW, Mercedes, and Subaru owners. They are a bit expensive though, costing about $46 for a 5-liter gallon.
3. Lucas Magnum CJ-4 Synthetic Heavy-Duty Diesel Engine Oil
Lucas is an American engine oil manufacturer, and their Magnum CJ-4 is another heavy-duty diesel engine oil. They claim the Magnum will reduce oil consumption, meaning you’re less likely to need to top up the oil. Lucas also claims their product will reduce engine wear, resists oxidation and thermal breakdown, and can extend oil drain intervals to 30,000 miles. Of course, you shouldn’t go that long without an oil change, it just means the oil is proven to last very long for better peace of mind.
A gallon (128 fluid ounces) of Lucas Magnum CJ-4 costs around $40, but they will usually sell it in a pack of four. But you can find promos online and a pack of four will usually cost around $112.
4. LiquiMoly Diesel High Tech Synthetic Motor Oil
LiquiMoly is a German automotive product manufacturer. They make many products from injector cleaner, engine flush liquids, and yes, synthetic oil as well. LiquiMoly claims their oil has low SAPS (sulfated ash, phosphorus, and sulfur), which is great for older diesel engines, and they’re perfect for diesel engines with diesel particulate filters (DPF).
The LiquiMoly Diesel High Tech synthetic oil comes in a 1L container which costs about $12.49, and a 5L container costing about $52. Keep in mind that these prices are the MSRP from LiquiMoly, and the price at retailers may vary.
5. Mobil 1 Turbo Diesel Truck Synthetic Motor Oil
Finally, we have the Mobil 1 Turbo Diesel Truck synthetic oil. They claim exceptional thermal breakdown resistance, as well as resistance to low-temperature sludge deposits. They claim it’s great for both high speed and stop-and-go driving conditions and is great for high-performance diesel engines.
The Mobil 1 Turbo Diesel oil comes in gallon containers (128 fluid ounces), and costs around $42. Oh, and they also come with a limited warranty that you may be eligible for.
Which One Should I Buy?
As far as we can tell, engine oils made by well-known manufacturers such as the ones we listed above are all very good. Reviews are generally positive, and the bad reviews are usually because of oil container leaks, which could be because of shipping. So it won’t affect the oil’s performance in your car.
Our advice is to read reviews and maybe try to find a customer that owns the same car as you do and see what they have to say. You can also search or ask on owner forums and see what oil the majority of owners recommend. And finally, European oil such as LiquiMoly may have been designed with European cars in mind. So, if you drive a Mercedes, BMW, Jaguar, or other European cars, choosing a European brand might be the best way to go.
Meanwhile, if you drive an American car with an American-made engine, choosing an engine oil from an American manufacturer is probably a good idea. Other than Lucas, other well-known American oil manufacturers include Pennzoil, Valvoline, and AMSOIL.
One last note, just make sure you get the oil with the appropriate viscosity grade for your engine. These are the numbers that you see on the oil containers, such as “15W-30” for example. We’ll discuss more down below in the FAQ section.
Questions & Answers
Got any more questions about oil for your engine? We’ll try to answer as many of your burning questions as possible below:
Is The Oil For Gasoline And Diesel Engines Different?
No, they’re pretty much the same. So, yes, you can use diesel oil in a gasoline engine and vice versa. However, we recommend using an engine oil that’s specifically rated for your engine type. This is because diesel engine oil typically has better soot resistance, and soot is inherent in diesel engines. So, if you have a diesel engine, it’s generally a good idea to use diesel-specific engine oil. Just to be safe.
What Do Those Numbers On The Oil Mean?
You may notice that there are numbers on the engine oil container. Most engine oils are now multi-grade, usually, the numbers are something like “SAE 15W-30”. But what do the numbers mean? Well, these numbers are the viscosity grade of the oil, or sometimes referred to as oil weight. It’s basically to tell buyers the viscosity characteristic of engine oil.
SAE stands for Society of Automotive Engineers, which is the association that came up with this numerical code system. Meanwhile, the “W” stands for “Winter”. This number indicates how easily the oil flows in cold temperatures. The lower the number, the better they flow in cold temperatures. Additionally, a lower number means they can operate in lower temperatures, sometimes as cold as -40°F. For certain engines, this can make turning it on much easier.
Meanwhile, the number afterward indicates the viscosity of the oil at operating temperature or 212°F. The higher the number, the easier the oil will flow at a higher temperature. Okay, but what does this all mean for you? Well, there are different engine designs out there. And these engines will require different oil grades; some need thinner engine oil, others can work with thicker engine oils. These numbers are there to tell you which type of oil you should get for your car.
As additional information, you should know old engine oil was single-grade, which means they had to be thick to get to the right viscosity at operating temperature since engine oils get thinner as they heat up. But thanks to additives, engine oil can now thin more slowly, which allows them to be thinner at cold temperatures (better flow during cold starts) but maintain the right thickness at operating temperature. This is why we now have multi-grade oils.
Which Engine Oil Viscosity Should I Use?
As mentioned, each engine will have different requirements. Check with your owner’s manual on which engine oil grade you should use, and make sure you use that on every oil change. If your manufacturer tells you to use 10W-30 oil, then always use engine oil with that viscosity grade. However, if you live in an area that gets very cold or very hot, ask your mechanic which oil grade you should use just to be safe. Sometimes the manufacturer’s recommendations don’t factor in extreme climates.
In any case, make sure to use the correct oil grade. Using incorrect oil can result in engine damage since certain oil grades may not work well with your engine. Using oil that’s thicker will put excess strain on your engine, resulting in performance loss and poor fuel efficiency. Meanwhile, if the oil is too thin, it won’t give enough protection for engine components. This will wear them down much quicker.
My Car Uses Conventional Oil, Can I Switch To Synthetic?
Yes, you can. All engines, new or old, can use synthetic oil even if the manufacturer filled it with conventional oil out of the factory. If anything, you will benefit from switching to synthetic oil and will help to protect your engine. But again, you don’t need to go out of your way to switch to synthetic oil. They offer more benefits, but the higher price means it’s not for everyone.
The same goes for the opposite: you can switch from synthetic oil to conventional motor oil. For example, if you’ve been using synthetic oil, but then you want to switch to conventional oil maybe because it’s cheaper, you can also do that.
Can I Mix Synthetic Oil With Conventional Oil?
Yes, but there are a few things you need to keep in mind. First, mixing synthetic oil with regular ones means you won’t have the benefits of synthetic oil. This is because the impure regular oil will dilute the additives in the synthetic oil, making them less efficient. So, you won’t benefit from the synthetic oil, and you’ll probably need more frequent oil changes as well.
Second, we recommend doing this only in an emergency. For example, let’s say you notice your engine is running rough. And after checking the oil dipstick, you notice that your engine is low on oil. If your engine is using synthetic oil, but you only have regular engine oil on hand, then it’s fine to mix them. Better to run on mixed engine oil rather than not enough oil.
The Oil On My Dipstick Is Black, Should I Change It?
A lot of people will advise you to change your oil when it has turned black, but this is a myth. Engine oil is supposed to get black over time, so there’s no need to worry when they’ve turned black. If you haven’t reached the recommended oil change interval, there’s no need to change your oil.
How Do I Change My Car’s Oil?
Changing your car’s oil yourself is a great way to save money since you won’t have to pay for labor costs. Here’s a quick guide:
- Jack up your car, put it on jack stands.
- Open the oil drain plug underneath your car with a wrench. Have an oil pan or other container ready, as the oil will immediately pour when you open the plug.
- You may also need to change the oil filter as well. It typically needs changing around every 10,000 miles.
- Put the drain plug back on.
- Fill in the engine with the appropriate oil in the correct amount, you can find how much oil your car needs in the owner’s manual. Wait for a few minutes, and then check the dipstick and see if it’s at the correct level. If it’s below the minimum level, fill it with some more. If it’s above the maximum level, you’ll need to drain some of the oil.
The video above is a great guide from ChrisFix on how to change your engine’s oil. His video is clear and very informative and is a great visual guide if you want to change your engine’s oil.
Best Synthetic Oil For Diesel Engines: Conclusion
Whether you drive a diesel or gasoline car, both will need regular oil changes. The intervals will vary depending on the car and the type of oil you use, so check your owner’s manual to find the manufacturer’s recommended interval.
Synthetic oil brings many benefits such as longer intervals, better engine protection, and possibly better fuel economy. But you don’t need to go out of your way to use synthetic oil for your diesel engine. Conventional oil will do the job just fine, although you will need more frequent oil changes.
The most important thing is to use engine oil with the correct viscosity grade for your car. If your manufacturer recommends 10W-30, then that’s the engine oil you should use. After that, use engine oil that’s been designed for your engine. If you have a diesel, it’s a good idea to use engine oils that’s been rated for diesel engines just to be safe. And finally, don’t forget to read customer reviews to make sure there aren’t any complaints regarding the oil’s performance. Hopefully, this article has been helpful for you.
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