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Diesel Guide: Different diesel grades in SA

We take a look at the different grades of diesel in SA, which consist of 10ppm, 50ppm and 500ppm.

Ntsako Mthethwa
January 29, 2024
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Diesel Guide: Different diesel grades in SA

The year 1892 will go down in history as the year when German inventor Rudolf Diesel created the first compression-ignition engine. The idea of a highly effective combustion engine that could turn all heat into useful labour motivated him.

Following a number of attempts, Diesel succeeded and called his invention a ‘compression ignition engine’  that used any fuel, and later on, his prototypes made use of peanut or vegetable oil to run. Strange, but true.

However, in 1897, he refined the invention and produced a commercially successful diesel engine, which was initially intended to replace stationary steam engines that powered factories and mills. That said, they were efficient and had higher torque ratings than steam engines, which made them suitable for their intended purpose.

In 1908, a utility truck became the first wheel-driven vehicle to employ a diesel engine, and the Citroen Company produced the first diesel car, dubbed the Rosalie, in 1933. Still, it didn’t reach production stages due to restrictions imposed on the diesel power plant, and it was only used as a prototype that was employed for testing and racing purposes. A few years later, in 1936, Mercedes-Benz produced the 260D, regarded as the first passenger car to wield a diesel engine.

Over the past 87 years, the evolution of diesel has been nothing but remarkable, with manufacturers from all four corners of the globe working hard to harness and refine the unit to make it a robust and efficient powerhouse, despite getting criticised for its environmental impact.

The truth of the matter here is that the journey of diesel technology doesn’t end there; it’s still being developed. We take a look at the different grades of diesel in SA, which consist of 10ppm, 50ppm and 500ppm. 

But before we outline the differences, it’s best to understand what the ‘ppm’ designation is. It’s an acronym for parts per million, which is a unit to measure sulphur in diesel fuel. For instance, diesel with emissions of 50ppm is considered cleaner than diesel with emissions of 500ppm, and since most diesel engines are sensitive to sulphur, measuring it is essential.  

Now you wonder why it’s such an important aspect of diesel production? Well, the adverse effects of sulphur include sulphur dioxide emissions, acid rain, foliage damage, less-than-ideal air quality and visibility, as well as respiratory illnesses.

10ppm Diesel

As its name suggests, 10ppm diesel contains 10 parts per million of sulphur, and with that said, it’s regarded as much cleaner than other diesel fuels simply because there are fewer traces of sulphur, thus making it favourable for its environmental benefits.

Normally priced slightly higher than the other types of diesel fuels due to a more advanced refining process and low sulphur content, 10ppm is generally good for vehicles as it prevents the accumulation of sulphur deposits in the engine and exhaust after-treatment system for cleaner and more efficient combustion.

Besides that, it has other benefits, such as improved efficiency and increased longevity of engine components. It’s recommended to always check with the vehicle manufacturer about which grade of diesel is suitable for your diesel vehicle. However, most modern diesel engines have been designed to run efficiently on ultra-low-sulphur-diesel (ULSD) fuel, while the classics may require fuel additives or modifications to prevent possible compatibility issues.

50ppm Diesel  

Regarding the 50ppm diesel, it simply contains 50 parts per million, which means it has more sulphur than the aforementioned 10ppm. While it isn’t cleaner compared to its 10ppm peer, the 50ppm is the most commonly used grade in South Africa in road cars and trucks and accounts for most local diesel consumption. This diesel grade has allowed the introduction of emissions control technologies in cars, such as diesel particulate filters and selective catalytic converters, to reduce emissions emitted by these types of engines.

50ppm diesel is often priced less than 10ppm, slightly higher than 500ppm and it’s compatible to run in most modern vehicles, yet a fraction of older diesel engines may require adjustments or modifications to run on ULSD fuel.

500ppm Diesel  

Unlike the 10ppm and 50ppm grades of diesel, 500ppm isn’t regarded as low-sulphur diesel because it contains 500 parts per million. 500ppm is, however, highly recommended for most heavy utility vehicles, such as trucks and heavy machinery, whose engines can function on less refined diesel and are designed to handle the higher sulphur content as well as the lower combustion quality of 500ppm diesel.

In conclusion, the benefits of using 500ppm diesel are mainly related to its lower price and wider availability. However, their drawbacks, such as lower fuel efficiency, poorer performance, higher emissions, and higher maintenance costs, outweigh these advantages.

Choosing the right diesel grade is important.

For diesel fuel to be where it is today, it has come a long way, evolving and diversifying to power a wide range of cars and machinery in various industries.

South African vehicle owners have the option to choose among different grades of diesel, each with its own set of characteristics and environmental effects. At the end of the day, it’s important to understand what your vehicle is compatible with and what its ppm designation means in order to make a knowledgeable decision.

The truth of the matter, though, is that diesel isn’t the cleanest form of transportation, and its heart beats strongest in the commercial fold, where it powers the trucks that transport goods throughout the world. But times are changing as electrification looms.

Until the day when electric commercial propulsion claims the spotlight and becomes widely accessible, diesel stands firm and continues to play its powerful note in the commercial sector.

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