What Is Quality Fuel and Why Is It Important?

April 23, 2024
fuel quality

From gasoline to diesel, fuel quality plays a critical role in the operation of vehicles, machinery, and equipment. It encompasses various factors such as purity, energy content, absence of contaminants, and compliance with regulatory requirements. 

In various industries, the use of high-quality fuel is essential for ensuring the efficient operation of processes and equipment. Reliable fuel quality ensures consistent machinery performance, minimizing downtime and maximizing productivity. 

Whether it's for personal vehicles, commercial fleets, or industrial equipment, using the best fuel quality is essential for ensuring reliable operation, prolonging equipment lifespan, and promoting environmental sustainability. 

What is Quality Fuel?

Fuel quality refers to fuel that meets certain standards and specifications, ensuring efficient operation within an engine or combustion system. High-quality fuel is free from contaminants and has a high energy content, ensuring robust engine performance.  

It also has a high octane rating, which measures the resistance of fuel to premature detonation or knocking in a spark-ignition engine. Higher octane fuels allow for more efficient combustion and enhanced engine performance while preventing engine damage.

Best fuel quality denotes higher cetane numbers that ignite readily upon injection into the combustion chamber, leading to smoother combustion, better fuel efficiency, and reduced emissions.

Impact of Quality Fuel on Vehicles

diesel quality

Using low fuel quality can have several impacts on your vehicle. Here’s an overview of a few of them.


Using low-quality fuel can be a bit cheaper than high quality fuel but it has detrimental effects on your vehicle. This includes incomplete combustion due to contaminants and lower octane and cetane numbers that result in reduced power output. Low diesel quality may also lack sufficient lubricating properties, leading to increased friction and wear within the engine's fuel system components. 


Poor-quality fuel results in higher emissions of nitrogen oxides, compounds of sulfur as well as VOCs, which have a deteriorating effect on the environment and human health. 

Engine health

Contaminants in low-quality fuel, such as dirt, debris, and sediment, as well as clog fuel injectors, disrupt the proper atomization and delivery of fuel into the combustion chamber, leading to decreased engine performance. If the fuel contains high levels of contaminants, it can overwhelm the filter and clog it more quickly, resulting in stalling or even engine failure if the flow is severely restricted.

Contaminants in low-quality fuel can include sulfur, lead, and other substances that can poison or coat the catalyst inside the converter, losing its effectiveness in converting pollutants and leading to increased emissions.

Maintenance Cost

Increased mechanical stress and strain due to degraded engine performance and poor fuel economy can lead to more frequent repairs, increasing maintenance costs for fleet owners.

Investing in high-quality fuel and adhering to recommended maintenance schedules can help mitigate these issues, ensuring optimal vehicle performance.

Impact of Quality Fuel on the Environment

diesel fuel quality

Air pollution

Emissions from burning low-quality fuel contribute to the formation of smog, which is a mixture of ozone, NOx, VOCs, and particulate matter that cause respiratory problems, cardiovascular diseases, and lung cancer. Sulfur dioxide and nitrogen oxides released during the combustion of low-quality fuel react with water vapor and oxygen in the atmosphere to form acid rain, which has detrimental effects on aquatic ecosystems, forests, soil, and infrastructure.

Climate Change

Low diesel quality not only puts a damper on engine performance but also the combustion process which magnifies the degrading effect on the environment through the increased emission of greenhouse gases

Greenhouse gases absorb and trap some of the outgoing infrared radiation within the ozone and increase the overall temperature of the planet, leading to global warming.

Environmental accidents

Spilled fuel can seep into the soil and leach into groundwater, posing risks to drinking water supplies and ecosystems. 

Improper fuel storage increases the risk of fires and explosions, posing safety hazards to nearby populations, infrastructure, and ecosystems. 

Standards of Quality Fuel in the US

The Environmental Protection Agency (EPA) establishes and enforces regulations related to fuel quality and emissions control under the Clean Air Act. The EPA also regulates fuel additives and mandates the use of emissions control technologies such as catalytic converters and particulate filters.

The American Society for Testing and Materials (ASTM) develops standards for various industries, including fuel and energy. Manufacturers often use these standards for safety procedures, fuel composition, performance, testing methods, and guidelines.

How to Measure Diesel Fuel Quality

There are various ways fuel quality can be measured to ensure its compliance with regulatory standards. 

Cetane Number Measurement

  • The cetane number of diesel fuel is measured using a cetane engine.
  • The fuel sample is injected into a combustion chamber, where it is compressed to a specified pressure and temperature.
  • The ignition delay period, which is the time between the start of injection and the start of combustion, is measured.
  • The cetane number is calculated based on the ignition delay period, with higher cetane numbers indicating shorter ignition delays and better ignition quality.

Sulfur Content Measurement

  • The sulfur content of fuel is commonly measured using analytical techniques such as X-ray fluorescence, X-ray diffraction, or ultraviolet fluorescence.
  • In XRF and XRD methods, the fuel sample is bombarded with X-rays, and the resulting emission or diffraction patterns are analyzed to determine sulfur content.

Density Measurement

  • A small volume of the fuel sample is placed in a calibrated chamber, and the buoyant force exerted by the sample to the chamber’s volume is measured to get the density.

Major Contaminants Affecting Fuel Quality


Water can enter fuel tanks through various means, affecting fuel quality, including condensation, cracks, and improper handling. It provides an ideal environment for microbial growth, which can lead to fuel degradation. Water also disrupts the combustion process by diluting the fuel-air mixture and reducing energy output.

Detection of water contamination in fuel can be done using water-finding paste, which is applied to a sampling rod or dipstick and inserted into the fuel tank. The color change of the paste indicates the presence of water. 

Ensuring storage tanks and containers are properly sealed, maintained, and inspected for leaks regularly can prevent water from entering and degrading fuel quality.


Microorganisms form biofilms, which are complex communities of microorganisms encased in a matrix of extracellular polymeric substances (EPS). Biofilms can accumulate on fuel filter surfaces, restricting fuel flow and decreasing engine performance. 

Bacteria utilize hydrocarbons in the fuel as a carbon source, reducing the energy content. They also produce acidic metabolites as byproducts of metabolism, which corrode metal surfaces in fuel systems.

ATP tests can detect microbial contamination in fuel samples since ATP is a molecule found in all living cells. Adding biocides to fuel tanks and keeping them dry can prevent microbial growth. 


Dirt and particulate matter can enter fuel during various stages of the refining, transportation, and storage processes due to inadequate handling. 

As the fuel flows through the engine system, these particles can cause friction and wear on critical components such as pistons, piston rings, cylinder walls, and bearings. Over time, this abrasion can lead to increased mechanical wear, reduced engine efficiency, and potential engine damage.

Dirt and other contaminants in fuel can clog fuel filters, restricting fuel flow to the engine, leading to fuel starvation and potentially reducing engine performance. Additionally, if the fuel filter becomes completely clogged, it may bypass unfiltered fuel to the engine, allowing contaminants to enter the system and exacerbating other problems. 

Installing high-quality fuel filtration systems, such as fuel filters and separators, and timely fuel polishing help to maintain fuel quality and ensure optimal performance of the engine. Regular inspection, cleaning, and maintenance of storage tanks prevent dirt and debris from entering the fuel.

Additional Factors Influencing Quality Fuel

The longer fuel is stored, the more time it has to undergo chemical changes such as oxidation and degradation. Oxidation of diesel fuel can lead to the formation of insoluble gums, varnishes, and deposits that can clog fuel filters, injectors, and combustion chambers.  

Fuel is also more prone to degradation when stored in hot and moist environments, which can lead to reduced fuel quality and microbial contamination. 

Common fuel additives include corrosion inhibitors, cetane improvers, and detergents, which help mitigate the effects of aging, oxidation, and contamination.

How to Store Diesel Fuel to Protect Fuel Quality

high quality fuel
  • Store fuel in clean, tightly sealed containers made of materials resistant to corrosion and contamination, such as metal or HDPE plastic. 
  • Choose a cool, dry storage location away from direct sunlight, moisture, and temperature extremes. 
  • To prevent older fuel from sitting unused for extended periods, practice regular stock rotation by using the oldest fuel first and replenishing stock with fresh fuel.
  • Keep fuel tanks and storage facilities clean. 
  • Consider using fuel additives, such as stabilizers, biocides, and corrosion inhibitors.
  • Implement a regular fuel testing program to monitor fuel quality and contamination levels.
  • Provide training to personnel involved in fuel handling, storage, and dispensing to ensure proper procedures are followed.

Choosing High-Quality Fuel

Choose fuel from reputable brands or suppliers known for their quality control practices and adherence to industry standards. Consider using fuels with additives such as detergents, stabilizers, and lubricity agents to maintain engine efficiency and reliability.

Using fuel with the correct octane rating for your vehicle is crucial for maintaining optimal engine performance and preventing potential damage. The octane rating of fuel refers to its resistance to premature detonation or "knocking" during the combustion process. 

Continuously running an engine on fuel with an octane rating lower than recommended can cause engine knocking and potentially damage to pistons, valves, and other engine components.   

FAQs (Frequently Asked Questions)

How often should fuel quality be tested in storage tanks?

Fuel quality should be checked at regular intervals, typically every 3 to 6 months. More frequent testing may be necessary in environments with higher contamination risks or where fuel turnover is low.

Can quality fuel affect the overall lifespan of an engine or machinery?

Yes, high-quality fuel with proper additives, correct octane or cetane ratings, and low contamination levels can help prolong the lifespan of engine components and maintain their efficiency.

How do seasonal changes affect fuel quality and storage?

Seasonal changes can affect fuel quality and storage conditions. Cold temperatures can cause fuel to thicken, while hot temperatures can accelerate fuel degradation and evaporation. 

How can consumers verify the quality of fuel at the point of purchase?

Consumers can verify fuel quality at the point of purchase by choosing reputable fuel stations or suppliers with good quality control practices. Look for certifications, such as ASTM or EPA standards, and check for signs of clean and well-maintained fuel dispensing equipment. Additionally, monitoring vehicle performance and fuel efficiency can help identify potential fuel quality issues.

How does fuel degradation affect fuel quality and engine performance?

Degraded fuel may form gums, varnishes, and deposits that can clog fuel filters, injectors, and combustion chambers, leading to rough idling, reduced power, and increased emissions.

Can fuel additives improve fuel quality, and are they necessary?

Fuel additives can improve fuel quality by enhancing stability, cleanliness, lubrication, and performance characteristics. While additives are not always necessary, they can be beneficial in certain situations, such as preventing oxidation, reducing emissions, and protecting engine components.

What are the long-term environmental impacts of consistently using low-quality fuel?

Long-term environmental impacts of using low-quality fuel include air pollution, smog formation, and environmental degradation. Additionally, fuel contaminants and additives may leach into soil and water, posing risks to ecosystems and human health.


Quality Fuel

Using high-quality fuel can significantly extend the lifespan of engines and machinery by reducing wear and tear on critical components such as fuel injectors, pumps, and valves. By choosing clean-burning fuels with low sulfur content and proper additives, we can help reduce air pollution and smog formation, protecting ecosystems and public health.

Clean, well-maintained fuel systems result in fewer breakdowns, repairs, and costly replacements, saving consumers money in the long run. By choosing reputable fuel suppliers, practicing proper fuel storage and handling, and using high-quality fuel additives when necessary, you can maximize the benefits of your vehicles and minimize your environmental footprint. Let's all commit to prioritizing fuel quality and adhering to best practices for the benefit of ourselves, our vehicles, and future generations. Get in touch with us today for a brighter, greener future!

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