Understanding Engine Oil Grades for Heavy-Duty Trucks

For heavy-duty trucks, the engine is the heart of your business. Keeping it running efficiently and reliably is important, and a crucial part of that is choosing the right engine oil. But with terms like "10W-40 E8/E11 Low SAPS" and "5W-30 E6/E9" flying around, it can feel confusing.

Well Relax! In this blog post, we'll break down the differences between these essential engine oil grades, explain the significance of "Low SAPS," and shed light on why some modern trucks are embracing even thinner oils like 5W-20 and 0W-20.

The Basics: Understanding Viscosity (e.g. 10W-40, 5W-30)

The numbers you see on an engine oil bottle, like "10W-40" or "5W-30," refer to the oil's viscosity. Viscosity is simply a measure of an oil's resistance to flow.

The first number (e.g., 10W, 5W): This indicates the oil's "winter" viscosity. The "W" stands for winter. A lower number here means the oil is thinner at cold temperatures, allowing for easier cold starts and faster lubrication of engine components when the engine is cold. This is vital for protecting your engine during those frigid mornings.

The second number (e.g., 40, 30): This represents the oil's viscosity at normal operating temperatures. A higher number means the oil is thicker when hot, providing a more robust protective film between moving parts under heavy load and high temperatures.

So, what's the difference between 10W-40 and 5W-30?

10W-40: This is a popular multi-grade oil for heavy-duty trucks, offering a good balance of cold-weather flow and hot-weather protection. It's generally a versatile choice for a wide range of operating conditions.

5W-30: This oil is thinner at cold temperatures than 10W-40, meaning it flows even more easily during cold starts. While slightly thinner at operating temperatures, modern 5W-30 formulas are designed to maintain excellent protection. The primary benefit here is improved fuel economy due to reduced internal engine friction, especially on start-up.

Beyond viscosity, engine oils for heavy-duty trucks also adhere to specific performance standards, most notably those set by the ACEA (Association des Constructeurs Européens d'Automobiles). These "E" series specifications are crucial for modern diesel engines, particularly those equipped with advanced exhaust after treatment systems.

What is "Low SAPS"?

SAPS stands for Sulphated Ash, Phosphorus, and Sulphur. These are elements found in traditional engine oil additives. While beneficial for engine protection, when burned during combustion, they can create ash deposits that clog and damage sensitive exhaust after treatment systems like:

Diesel Particulate Filters (DPFs): These capture soot and particulate matter from exhaust gases.

Selective Catalytic Reduction (SCR) systems: These use Diesel Exhaust Fluid (DEF/AdBlue) to reduce nitrogen oxides (NOx) emissions.

Low SAPS oils are specially formulated with significantly reduced levels of these elements. This is vital for:

Extending the life of DPFs and SCRs: By minimising ash build-up, low SAPS oils help these systems function efficiently for longer, reducing the need for costly maintenance and regeneration cycles.

Maintaining emissions compliance: They ensure your truck continues to meet strict environmental regulations.

Potentially improving fuel economy: A cleaner, more efficient after treatment system means less strain on the engine.

Understanding the ACEA E-series evolution:

E6/E9: These were the primary low SAPS specifications for heavy-duty diesel engines. E6 generally signified a lower SAPS content than E9, often for Euro IV/V engines. E9 was more widely adopted for Euro V and early Euro VI engines.

E8/E11 (Previously E6/E9): The ACEA has recently updated its classifications. What was known as E6 and E9 has now transitioned to E8 and E11, respectively, reflecting ongoing advancements in additive technology and engine requirements.

E8: Generally aligned with the stricter low SAPS requirements, often for engines with highly sensitive after treatment systems.

E11: Represents a more robust, long-drain interval low SAPS oil, suitable for a broader range of modern heavy-duty engines.

When choosing oil, always consult your truck's manufacturer manual. It will specify the exact ACEA performance category required for your engine.

The Future is Thinner: 5W-20 and 0W-20

You might be hearing more about even lower viscosity oils like 5W-20 and 0W-20 making their way into heavy-duty truck applications. This trend is driven by several factors:

Fuel Economy: Thinner oils reduce internal friction within the engine, leading to measurable improvements in fuel efficiency. In an industry where every penny counts, this is a big advantage.

Reduced Emissions: Lower friction also contributes to lower emissions, aligning with increasingly strict environmental regulations.

Advanced Engine Design: Modern heavy-duty diesel engines are engineered with tighter tolerances and more sophisticated internal components that are designed to operate optimally with these lower-viscosity lubricants.

Key points about 5W-20 and 0W-20:

0W-20: Offers the best cold-start performance, providing immediate lubrication even in extremely cold climates.

Full Synthetics: These ultra-low viscosity oils are almost exclusively full synthetic formulations. Synthetic oils offer superior stability, resistance to breakdown, and performance across a wider temperature range compared to conventional or semi-synthetic oils.

Important Note: While the benefits are clear, it's crucial to only use 5W-20 or 0W-20 if your truck's manufacturer specifically recommends it. Using an oil that is too thin for an engine not designed for it can lead to poorlubrication and potential engine damage.

Making the Right Choice for Your Fleet

Selecting the correct engine oil for your heavy-duty trucks isn't just about pouring liquid into a sump. It's about optimizing performance, protecting vital components, ensuring compliance, and ultimately, saving on operating costs.

Always refer to your vehicle's owner's manual for the precise viscosity grade and ACEA specifications recommended by the manufacturer. Consider your operating climate and the type of duty your trucks perform. And when in doubt, consult with a trusted lubricant supplier who can help you navigate the complexities of modern engine oils and find the perfect match for your fleet.

By understanding the information above, you can make informed decisions that keep your heavy-duty trucks running smoothly, efficiently, and profitably for miles to come.