A Performance Oil Change Should Be Part Of Your Diesel Maintenance

Having a proper maintenance schedule is paramount to ensuring the engine in your truck lasts as long as possible. Without proper maintenance, things will wear out long before they should. That is why a regularly scheduled oil change must be a key part of that maintenance procedure. Let’s face it, even the best engine oils break down over time. We recently worked with a local shop to replace a set of head studs in a Cummins-powered Ram and since it was not known when the truck had its last oil change, we decided to also change the oil when we finished.

But, with so many available lubricants and additives on the market, which one to choose can be a daunting task. Most guys just go to the local big box store and buy what they think (or hear on the internet) is right for their truck, never considering the complete oil system needs. We’ll go on record saying that, for this truck, we decided to employ a full synthetic from Liqui Moly. But, which oil was needed was the next question.

oil change

No matter what brand of oil you decide to run in your diesel, make sure it meets the specifications called for by the manufacturer. Requirements change quite often and using an oil that doesn’t meet specifications can result in that engine not living a long and happy life.

To choose the right lubricant for your vehicle, the original equipment manufacturer (OEM) typically offers its recommendations in regard to viscosity and certifications. Viscosity grades are primarily recommended according to the expected ambient temperatures, particularly the starting temperatures.

An engine oil’s operating temperature does not change significantly even in different ambient temperatures, so the recommended viscosity is quite consistent for various applications. The main difference is the first number (viscosity grade “W”), which relates to the “cold weather” starting temperature viscosity, as this will determine the lubricant viscosity, its ability to be pumped, and its readiness to lubricate the engine.

oil change

This chart gives some basic guidelines for selecting the right viscosity oil, but always refer to your truck’s owner’s manual for the factory-recommended oil viscosity.

When it comes to viscosity, a 5W viscosity grade will flow more easily at lower temperatures than a 15W oil (bearing clearances and such being the same). Because of that, it is expected to be used in regions that experience low temperatures. In tropical areas, most OEMs will recommend a “thicker” product, like a 15W, because the warmer temperatures allow the thicker oil to flow easier.

Another important consideration when choosing engine oil is the quality certification or performance level. In the U.S., this is determined by the American Petroleum Institute (API). For diesel oil, quality levels are rated by a two-letter designation. The letter “C” is used along with a second letter that is assigned according to the alphabet sequence, starting with “A” for the lowest performance rating to “K” for the most recent and highest performance. In addition, for some applications, there are specific OEM performance requirements that are also a condition of the engine’s warranty.

On the other hand, you can use a 5W viscosity grade in warmer climates when a 10W or 15W is recommended if you want to provide faster lubrication to engine components during start-up. However, there are some drawbacks to consider. For instance, since a lighter base stock is used in the 5W formula, the lubricant may have more evaporation than a 10W or 15W. The 5W might also cost more than the 15W and break down more of the viscosity improver additives in the formula.

To say that all oil changes are the same would be a disservice to the Liqui Moly performance oil change. According to Peter Szarafinski of Liqui Moly, “the ‘performance oil change’ turns an ordinary oil change into a rewarding chemical treatment for the truck. It works like this: Right before the oil change, add Pro-Line Engine Flush to the old oil and let the engine idle for 10 to 15 minutes. During this time, the cleaning agents dissolve contaminants and deposits which are then drained together with the used oil. The fresh oil enters a clean engine and is able to deliver its full performance.”

oil change

The first step in our performance oil change had us adding Liqui Moly’s Pro Line Engine Flush to the engine before draining the old oil. This liquid captures dirt and carbon deposits and removes them from the engine as the old oil is drained.

Picking the right oil is crucial with any engine, and knowing the specifications required for a particular engine is a must. “Today, oil is like a fluid spare part which needs to fit precisely to the engine,” says Szarafinski. “Using the wrong oil is like installing a spare part that does not fit. The oil guide at www.liqui-moly.com tells exactly which oils are the right ones for a specific truck.”

We were thinking long-term with this truck, so we decided to include Special Tec AA SAE 5W-40 diesel oil. This is a fully synthetic low-viscosity oil, developed to meet the high demands of modern Asian and American diesel engines. The innovative additive technology guarantees the best wear protection and engine cleanliness, the lowest oil and fuel consumption, and the highest engine efficiency possible. It is ideally suited for engines with diesel particulate filters (DPF) and turbochargers.

oil change

When choosing an oil, more than just viscosity matters. Sure, you need to utilize the right viscosity, but you also need an oil that meets the requirements of your truck engine’s manufacturer. In our case, Cummins specifically recommends 15W-40 oil for temperatures above 0 degrees Fahrenheit while the 5W-40 is safe for warm and cold climates but is highly recommended for extremely cold temperatures.

Since the truck getting the new oil is located in Florida, cold weather is not a concern. That means a 15w oil would suffice, but we still opted to utilize a 5w viscosity as it will flow and coat surfaces much quicker during initial startups. Also, the Liqui Moly oil does carry an API rating of CK-4 so it does meet the requirements for the Cummins engine.

After the new oil was added to the engine, we included Truck Series Oil Treatment to the fresh oil. This is an oil additive developed especially for the needs of these workhorses. It was developed to reduce friction and allow the engine to free up more power. What’s more, it protects the engine from wear and tear, even under extreme conditions.

Although Liqui Moly oil is all-inclusive in regard to additives, I asked Szarafinski about adding the Liqui Moly Oil Treatment and he had this to say, “is Oil Treatment necessary? No, it is not. It is like washing your hands. Using just water does the job, but if you also use soap, it is better. Oil Treatment adds additional performance to the engine by improving the already existing anti-wear properties of the oil.”

As Szarafinski eluded to, using the correct oil is something that not many enthusiasts consider. They feel buying nearly anything should suffice. It might, in the short term. Liqui Moly offers a wide range of oils designed to suit nearly every vehicle — both new and old. All of the company’s oils are made in Germany, and there is an oil for gas and diesel engines, with fully synthetic, synthetic blends, and even mineral-based oil available.

Szarafinski adds, “finally, pour a can of Truck Series Complete Diesel System Cleaner in the fuel tank. Its cleaning agents remove deposits from the injector, thus restoring the original, effective spray pattern which delivers a better power output.”

With the engine’s internals clean and enjoying fresh oil, we finished out maintenance with a can of Deisel System Cleaner to clean the injectors.

According to Liqui Moly, this is an effective mixture of additives for the rapid removal of performance-diminishing deposits from the fuel system in all kinds of diesel engines. It cleans the injectors and the combustion chamber. With cleaner injectors, proper fuel atomization is achieved for improved engine efficiency. It is suitable for use in all diesel engines, with or without turbochargers. It is also safe for use with catalytic converters and diesel particulate filters (DPF).

A Liqui Moly performance oil change isn’t some magic formula that will make your truck’s engine better than new. However, it is a regimen of automotive chemicals that will help to restore your truck or SUV’s original performance. The more miles your truck has, the more built-up deposits are present, and the more of an effect you’ll experience from a performance oil change.

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Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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