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Debunking 5 Synthetic Diesel Oil Myths

Do you know your oil knowledge? Here are five myths of synthetic diesel oil that might surprise you.

Hillary Weiss
Hillary WeissSenior Editor
May 22, 2023
Debunking 5 Synthetic Diesel Oil Myths

Do you know these five myths about synthetic oil?

Photo: Work Truck

4 min to read


Synthetic oil plays an important role in ensuring the smooth functioning of all engine components.

It allows the various parts of your engine to work harmoniously, promoting optimal performance and longevity.

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However, there are misconceptions regarding engine oil which leads to confusion.

A combination of factors such as information overload, technical complexities, marketing strategies, and individual experiences can contribute to the existence of misconceptions about synthetic diesel oil.

Fortunately, Shell Rotella shared synthetic oil’s common myths and why they are incorrect.

With their expertise, they help you distinguish fact from fiction, enabling you to make informed decisions about your work truck engine's lubrication needs.

5 Common Synthetic Diesel Oil Myths

From new engines, to switching back to mineral oil, we’ve got yu covered on the top five synthetic diesel oil myths and info on why they’re myths.

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Myth 1 — Once You Use Synthetic Oil, You Can’t Go Back

Transitioning back to conventional oil from synthetic oil is completely safe and poses no risks.

You can do so without any concerns as you transition from the 5W-40 synthetic oil typically used in winter to a 15W-40 conventional oil suitable for spring.

Karin Haumann, the OEM Technical Manager for Shell Lubricants, highlights the importance of using lower-viscosity oil, such as synthetic oil, during colder months to enhance engine stability.

Haumann also emphasizes that while a synthetic oil can meet the exact specifications of conventional oil, it's essential to consider the inherent benefits that a full synthetic product can provide.

With the proven advantages of synthetic oil, you can use it in your engine all year round.

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Myth 2 — Synthetic Oil Is Expensive

While synthetic blend and full synthetic oils may have a higher initial cost, their advantages make them worthwhile investments.

For example, Shell Rotella T6 Full Synthetic engine oils are designed to deliver protection while also offering the potential for improved fuel economy.

This means you can save on fuel costs without compromising the engine's performance or durability.

Key benefits of synthetic oil include:

  • Reduced oil consumption, leading to lower maintenance costs over time.

  • Enhanced protection against oxidation, resulting in increased fuel economy.

  • Excellent corrosion control, safeguarding critical engine components.

  • Low Ash formulation, ensuring compatibility with emissions systems.

Myth 3 — Synthetic Oil Is for New Engines Only

Synthetic engine oils are engineered to deliver enhanced protection under various demanding conditions, catering to new and older engines.

Whether you frequently engage in stop-and-go driving or operate your work truck in extreme temperatures, synthetic engine oils are specifically formulated to provide the following benefits:

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  • Improved engine protection: Synthetic oils offer superior protection to your engine components, safeguarding them against wear, friction, and potential damage.

  • Engine cleanliness: Synthetic oils help maintain a cleaner engine by preventing the buildup of sludge, deposits, and contaminants that can impede performance.

  • Temperature regulation: Synthetic oils help keep operating temperatures cooler, which is crucial in high-stress or extreme temperature conditions, ensuring optimal engine performance and longevity.

  • Cold-weather lubrication: Synthetic oils possess excellent cold-weather properties, allowing them to lubricate the engine quickly and effectively during start-up in cold climates.

If your truck is designed for higher performance, it will experience increased stress and demand. In such cases, opting for a synthetic oil is recommended as it is better equipped to withstand elevated stress levels and provide optimal protection.

Myth 4 — You Can’t Switch Oil Brands

If the new oil meets the specifications and approvals required by your engine's manufacturer, switching between different oil brands poses no concerns.

It's worth noting that while multiple oil brands may meet industry and OEM specifications, they often exhibit varying performance levels.

Myth 5 — High Viscosity Oil Is Better

The choice of oil viscosity for work trucks depends on several factors, including the specific requirements of the truck's engine and operating conditions.

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While high-viscosity synthetic oil can provide certain benefits, it may not always be optimal for work trucks.

In some cases, work trucks with heavy-duty engines and high operating temperatures may benefit from higher viscosity oils, such as 15W-40 or similar grades, to provide adequate protection under demanding conditions. These oils can offer enhanced wear protection and better resistance to oil breakdown, ensuring the longevity of engine components.

Oil is available — like Shell Rotella T6 10W-30 — that offers the advantages of a full synthetic oil in the rapidly growing viscosity grade for diesel-powered vehicles.

This versatile oil not only provides fuel economy benefits but also delivers excellent engine protection for hardworking trucks.

These oils perform well even in heavy-duty diesel engines and extreme temperature conditions.

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