Diesel types and fuel use: S10, S500, regular and additized

Anyone who manages a fleet knows that diesel is one of the main operating costs. But can the type of diesel used really influence a truck's fuel consumption?

Between regular and additized diesel, S10 and S500, the wrong choice can not only increase consumption, but also affect engine performance and durability. It is also worth keeping track of the mandatory blend of biodiesel in diesel in Brazil, because it becomes part of the refueling, inventory, filtration and preventive maintenance routine.

If you want to understand which diesel is more economical and which makes the most sense for your fleet, keep reading and check out:

• Can the type of diesel change a truck's fuel consumption?
• What is the difference between regular diesel and additized diesel?
• What happens if you use S10 diesel instead of S500?
• What is the best diesel for a fleet truck?
• Which diesel burns more?
• What makes a truck's fuel consumption go up?

Can the type of diesel change a truck's fuel consumption?

Many managers wonder whether the type of diesel affects the vehicle's consumption. The answer is yes – and understanding this relationship can make all the difference in operating costs.

This happens because each of these types has a specific chemical composition, with variations in the amount of sulfur, lubricating power and the presence of additives.

In addition, in Brazil commercial diesel receives a mandatory blend of biodiesel, a rule set out in Law No. 11.097/2005. As of August 1, 2025, the blend became 15% biodiesel, known as B15. Since biodiesel is intended mainly for compression-ignition engines, it is part of the operating reality of diesel trucks.

Additized diesel, for example, contains detergents and dispersants that help keep fuel injectors clean, ensuring more efficient atomization of the fuel in the combustion chamber. This can improve diesel combustion and, as a result, reduce consumption.

Biodiesel also enters this discussion because of lubricity and cetane number: the blend can improve these characteristics of the fuel. At the same time, the fleet needs to take care of storage quality and filtration, since the biodiesel specification involves controls for stability, distillation and tests related to proper filtration, deposits and clogging in fuel injectors.

S10 and S500 diesel, on the other hand, differ in sulfur concentration, which can affect the performance of engines designed for one type or the other. Using an unsuitable diesel can cause carbon deposits, impairing combustion and increasing the truck's consumption.

That is why choosing the right fuel makes all the difference in fleet savings and engine useful life. With B15, this choice should also come with attention to filters, fuel injectors, refueling history and preventive maintenance.

Diesel prices in the fleet: separate the market, public measures and internal control

A price change should not be analyzed in isolation. To understand the cost of diesel in the fleet, separate three fronts: the movement observed in the market, temporary public measures and the operation's own data. In Brazil, the ANP (National Agency of Petroleum, Natural Gas and Biofuels) publishes spreadsheets with the results of the weekly surveys of its Fuel Price Survey, which can serve as an external reference for comparison.

Public measures also need to be recorded with their duration and scope. In one federal announcement in Brazil, for example, an additional subsidy of R$ 1.40 per liter of imported diesel A for road use was planned, for a period of 30 days. This does not replace the analysis of the price actually paid by the fleet, nor should it be treated as a permanent reduction.

In the internal routine, compare the price by supplier, the volume refueled, consumption and maintenance events in the same period. Avoid attributing every cost increase only to the price at the pump: changes in route, load, driving, filters and the injection system can also affect the result. To go deeper into this analysis, see the posts on rising diesel prices, diesel savings and fuel price increases.

What is the difference between regular diesel and additized diesel?

The main difference between regular and additized diesel lies in the components added to the fuel to improve engine performance.

• Regular diesel: the most basic type of diesel, without special additives. It meets the minimum lubrication and combustion requirements, but can leave dirt deposits in the fuel injectors over time.
• Additized diesel: contains detergent and dispersant additives that help keep the injection system cleaner, preventing residue formation and providing more efficient combustion.

In practice, additized diesel can bring benefits such as lower fuel consumption, reduced pollutant emissions and a longer useful life for engine components.

For fleets that travel long distances and want to optimize vehicle performance, adopting refueling management practices can be essential to optimize vehicle performance and reduce waste.

When the operation buys, stores or keeps track of diesel with biodiesel, refueling management also helps identify variations in consumption, set aside problematic batches, reinforce filter replacement and record refueling and maintenance events.

What happens if you use S10 diesel instead of S500?

S10 and S500 diesel differ in the amount of sulfur, and this can have a direct impact on how the engine works.

• S10 diesel has only 10 parts per million (ppm) of sulfur and is recommended for modern engines with emission reduction technology (such as trucks with SCR and EGR systems).
• S500 diesel has 500 ppm of sulfur and is indicated for older engines that do not have advanced emission control systems.

Switching back and forth between these two types of diesel in the vehicle can cause consequences and losses for the fleet. If an engine developed for S10 is filled with S500, there may be residue buildup and higher pollutant emissions, in addition to risks of failure in the exhaust aftertreatment system.

In other words, always follow the manufacturer's recommendations to avoid mechanical issues and unnecessary maintenance spending.

The same logic applies to any change of fuel or blend: before standardizing refueling, check the manufacturer's recommendation and the engine warranty. This check is even more important when the fleet is evaluating blends with biodiesel, because compatibility may depend on the engine design and the conditions of use.

What is the best diesel for a fleet truck?

There is no single ideal type of diesel for every fleet. The choice of the best fuel depends on the truck model, the engine technology and the operating conditions.

In general, consider the following points:

• If the fleet has modern trucks (Euro 5 and Euro 6): the most recommended option is S10 diesel, to avoid damage to the emission system.
• If the trucks are older (prior to Euro 5): S500 diesel can be used without harming the engine.
• If you are looking for better efficiency and lower consumption: additized diesel can be a good investment to reduce residue and improve fuel combustion.
• If the operation needs to keep track of B15: maintain a filter inspection routine, watch for signs of clogging in the fuel injectors and record refueling and maintenance events.

Ideally, always analyze the cost-benefit for the particularities of your operation. Additized diesel may have a slightly higher price, but it can pay off in fuel savings and in reduced corrective maintenance costs.

In the case of B15, the point is not choosing whether or not the blend is present in commercial fuel, but preparing the fleet to operate well with it: refueling at reliable suppliers, keeping track of the quality of the fuel received, keeping filter replacement up to date and servicing the injection system when consumption increases or there are signs of clogging.

Which diesel burns more?

Diesel combustion depends on its composition and on the quality of combustion in the engine.

Additized diesel tends to burn more efficiently, because it keeps fuel injectors clean and improves fuel atomization, reducing waste.

Regular diesel, on the other hand, can create carbon deposits over time, impairing combustion and increasing fuel consumption.

In addition, diesel combustion is also influenced by factors such as engine tuning, fuel quality and the maintenance of injection system components.

With biodiesel in the blend, fuel stability and storage conditions also deserve attention. The Brazilian specification has required the use of an antioxidant additive in biodiesel since 2019 to help prevent the product from degrading along the supply chain, but the fleet still needs to maintain good practices for purchasing, storing and renewing fuel.

What makes a truck's fuel consumption go up?

Besides the type of diesel, there are other factors that can increase the fleet's fuel consumption, such as:

• Lack of engine maintenance: dirty fuel injectors, clogged fuel filters and injection system failures compromise combustion efficiency.
• Incorrect tire calibration: underinflated tires increase rolling resistance, forcing the engine to burn more fuel.
• Excess weight: carrying loads above the vehicle's capacity requires more effort from the engine, increasing consumption.
• Inappropriate driving: harsh acceleration, excessive braking and very high speeds increase diesel use.
• Use of low-quality fuel: adulterated or off-spec diesel can impair combustion and increase consumption.
• Filters and injection left unchecked: with B15 or any diesel outside ideal conditions, dirt, fuel degradation and filtration failures can increase corrective replacements.

To avoid waste and make each refueling as efficient as possible, it is essential to keep a close eye on the truck's consumption and implement good refueling management practices.

It is also worth connecting refueling and the workshop: record where the vehicle refueled, when filters were replaced, which issues appeared in the injection system and whether consumption increased after a given batch. This routine helps tell apart a fuel issue, overdue maintenance and inappropriate operational use.

Want more precise control of your fleet's refueling and fuel consumption? Download the free refueling control spreadsheet now (in Portuguese)!