Best Oil for Diesel Engines

Is synthetic oil better for diesel engines when compared to conventional diesel motor oils? We’ll try to answer that question in this blog post.

The first question we must ask is what is synthetic motor oil and is it the best oil for diesel engines? Synthetic motor oil is manmade and chemically engineered to create a pure lubricant. Pure means that the synthetic oil contains no harmful contaminants. Also, the molecular structure of synthetic oil is designed for specific purposes. There’s much thought and planning put into creating an oil with all the important features so that the oil delivers real benefits to the user.

A quality and high-performance synthetic oil is versatile. Due to its uniform molecular structure, it imparts properties that deliver superior friction reduction, stronger film strength, the ability to function in a vast range of temperatures, and improved fuel economy. These enhanced properties are so advanced and effective that they put synthetic oils’ performance far beyond the reach of what any conventional lubricant can provide.

Why Choose Synthetic Oil?

Conventional lubricants are the antithesis of synthetic oil. First, crude oil is taken from the ground and sent to a processing plant where it is refined. The majority of the refining process is to grab gasoline or diesel fuel. The base oils that are leftover are used for making lubricants and other products.

Inherently found in crude oil are ingredients that are not contributing to the performance of the lubricant. In fact, from the get-go, conventional lubricants contain contaminating elements such as nitrogen, oxygen, sulfur, and metal components such as vanadium and nickel. Unfortunately, these unwanted ingredients cannot be completely extracted via the refining process.

When the crude base oils are put through the refining process, it separates different types of molecules that make up the oil by weight. The molecules found in conventional lubricants are similar in weight but dissimilar in molecular structure.

By having a dissimilar molecular structure, conventional lubricants cause the oil to perform at a much inferior level of performance than synthetics. Their performance is inferior during cold weather, they offer lower levels of film strength, they burn much easier and faster than synthetics, they deliver less service life, they create more fluid friction, and thus they cause diesel engines to expend more power and consume more fuel.

Remember, we’ve just briefly explained that conventional lubricants inherently contain contaminants right in the bottle before you pour them into your engine. This means right from the get-go that you’re pouring in potentially damaging contaminants before that oil has even been called into service. On the flip side of that coin, synthetic oils are purposely engineered to be pure and free of any contaminants.

Now that you have this bit of information, when you see two bottles on the shelf, one conventional diesel oil that already contains contaminants that could not be removed from the refining process, and the other a diesel synthetic oil that is pure and contains no contaminants, then hopefully you would choose the latter.

Improved Fuel Economy

The next area that could help answer the question “is synthetic oil better for diesel engines?” would be whether a lubricant can in fact improve fuel economy. As previously stated, synthetic oils are laboratory engineered with a uniform molecular structure. Conventional oils, unfortunately, contain molecules with an uneven or dissimilar structure.

The huge advantage that synthetic lubricants offer due to their uniform molecular structure allows the oil to flow without any fluid friction. Their superior flowability has a huge impact on not only reducing friction in a diesel engine but also translates to an engine performing easier and freer, thus delivering an improvement in fuel efficiency.

One cannot say the same thing concerning conventional lubricants. Their uneven molecular structure in fact creates too much fluid friction, which is the exact opposite of synthetic oils. This fluid friction becomes even worse as the temperatures become colder. The simple decision in switching to synthetic oils can make an immediate impact on your bottom line and your wallet.

If your goal is to improve fuel economy in your fleet from 1-3%, then switching to a high-performance 100% pure synthetic diesel oil can be a real possibility.

It is a known statistic in the engine industry that 80% of engine wear occurs during initial cold dry starts. That is unfortunately an amazing statistic. Once you hear that, it sounds like a very scary scenario. The goal, then, is how to vastly reduce that number down. In a perfect world, it would be nice if the oil lubricating and protecting critical engine components never dripped back to the oil sump when the engine was shut down.

Unfortunately, when an engine sits overnight, all that important lubricating oil drains back completely into the oil drain tank. When you turn the ignition switch on and start your engine, there is a moment in time when the engine parts do not have this important lubricating oil protecting them from wear. This is why it has been found that 80% of engine wear occurs during these dry starts.

It is now extremely significant to understand the differences in molecular structure between synthetics and conventional oils. As we’ve already stated, synthetic oil molecular structure is uniform, thus delivering a lubricant that flows without friction and flows easily. Its ability to flow so easily is absolutely the type of lubricant required during cold dry starts. Again, conventional lubricants are not very good at quickly flowing throughout your diesel engine when first starting your motor.

It takes petroleum diesel oil a lot longer to travel throughout all the engine oil galleys and reach critical engine parts. Hands down, 100% pure synthetic oil delivers up to 6 times better wear protection than conventional oil. Also, there is another unique characteristic to a quality high-performance pure synthetic oil. It offers superior clingability, or stickiness. This means that a lot less oil will drain back into the oil sump when shut off. The oil tends to stick and stay on critical engine components while it sits idle.

Depending on the chemistry and the choice of synthetic base stocks used, a premium high-performance synthetic diesel engine oil will have what is called “polar molecules.” This polarity causes the oil to cling to the metal surfaces like a magnet.


Protecting Your Engine Synthetically

The fact of the matter is conventional oils are engineered to meet a low price. They simply cannot compete from a performance point of view with 100% pure synthetic oils. Realistically, their levels of performance can only handle light-duty environments. They are not capable of handling severe operating conditions for long periods of time. They are not naturally predisposed to deliver the kind of performance features and great benefits that an engineered diesel synthetic oil can deliver.

It is conventional oils that are found in engines that were tested that determined the statistic that 80% of engine wear occurs during cold dry starts. They just don’t flow fast enough to lower that number of 80%. This type of wear leads to wear on cylinder liners and rings, which causes increased oil consumption and a loss of compression.

This results in a reduction in power and fuel mileage. The only solution in vastly lowering cold dry start wear in your diesel engine is to seriously consider switching to a high-performance 100% pure synthetic diesel oil.

Extreme Temperature Performance

High-performance 100% pure synthetic base stock oils are naturally thermally stable. This means that a quality synthetic base oil will resist heat or thermal breakdown. Conventional oils are nowhere near as thermally stable as synthetic oil.

When the temperatures start to spike when your engine is working hard during hot summer months, you want to be sure that your engine contains 100% pure synthetic oils that are thermally stable. When it comes to sub-zero temperatures, pure synthetic oils and cold weather go together. Synthetic oils were specifically designed to handle extremely cold weather conditions. They flow easily down to minus 60 degrees Fahrenheit.

One of the main reasons they’re able to is that they contain no wax. Unfortunately, conventional oils do contain wax, and when it gets cold, conventional oils tend to thicken rather quickly. It is critical that your engine contains oil that flows without any hindrance during sub-zero temperatures. This is absolutely true during sub-zero dry starts. This is where synthetic oils earn their keep. They protect and reduce engine wear.

No matter whether the temperature is very hot or very cold, a high-performance 100% pure synthetic diesel oil can easily handle both situations.

Controlling Lubricant Viscosity

When a lubricant chemist decides to engineer a high-performance pure synthetic diesel engine oil, only the finest quality synthetic base oils are chosen. These top tier synthetic base oils will naturally be resistant to any oxidation and also easily cope with any potential thickening effects of soot contamination. They’re resistant to both. Additionally, only the finest heavy-duty detergent/dispersant additives will be utilized. These robust detergents/dispersants are added to keep soot particles suspended.

By keeping soot particles suspended, it helps prevent any potential formation of larger wear-causing contaminants. The synergy between carefully selected base oils and detergent/dispersant additives helps maintain the correct viscosity and eliminates any soot related wear. Due to these high-performance pure synthetic base stock oils being thermally stable, they deliver far less volatility, which translates into maintaining the oil’s viscosity even after it may have been exposed to extremely high temperatures.

Choosing to use state-of-the-art synthetic oil designed for diesel engines will provide you with the maximum engine protection and efficiency.

Reducing Oil Consumption

The diesel engine market is full of different choices when trying to decide which engine oil to use. If your goal is to provide your engine with the maximum possible protection and to protect your heavy investment in your equipment, then we suggest you take a serious look at only those oils that are custom blended and formulated to provide absolutely state-of-the-art performance.

There is a science and definitely secrets that have been gained through experience by certain synthetic oil manufacturers. Experience does matter when formulating the best diesel oil. For example, when researching what oil you might choose, see if the manufacturer offers any test data and any facts to back up their claims.

For example, if you have Caterpillar equipment, how does the oil meet and stack up to the API CK-4 standard? Has it been tested to see how it deals with oil consumption. If the oil can provide better than 60% less oil consumption during the Caterpillar-1N Oil Consumption Test, then that oil is definitely a contender to be one of the finer oils on the market.

It is important that oil offers a low rate of burn-off or volatility. This means your engine will consume far less oil than a conventional lubricant. By consuming less oil, less oil vapor will be introduced into the combustion chamber. You do have to invest some time in researching and comparing stats/data between one company and another. There are a few companies out there that stand out from the crowd.


Turbo Cleanliness

You may have some turbocharged diesel engines in your fleet. Without a doubt, synthetic diesel engine oil needs to be in those engines. High revving turbos require the best oil for diesel engines. Synthetic oils will typically keep a turbo much cleaner than conventional oils will. 100% synthetic oils are designed to withstand the extreme demands placed on turbos when the equipment is pulling heavy loads or when the turbo is being called on to generate max horsepower.

The last thing you want is a turbo or engine failure. It is much cheaper to change your oil than changing engine or equipment parts.

What is the Best Oil for Diesel Engines?

Hopefully, this blog post has given you some food for thought. You’re interested in longer engine life, less engine wear, longer drain intervals, less oil consumption, better engine efficiency, improved fuel economy, and lower maintenance costs. Synthetic oils can provide these types of excellent benefits.


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